Bone block assemblies and their use in assembled bone-tendon-bone grafts

ABSTRACT

The present invention has multiple aspects. In its simplest aspect, the present invention is directed to an intermediate bone block comprising a machined segment of cortical bone, cancellous bone or both, the intermediate having a face comprising one to ten compression surfaces and one to ten cavities, the compression surfaces suitable for compressing soft tissue, the cavities for receiving and holding overflow soft tissue. The cavities are preferably channels, and more preferably channels having an omega cross-sectional profile. The invention is also directed to bone block assemblies suitable for binding to a soft tissue to form an implantable graft, and to such implantable grafts. A particularly preferred graft is a bone-tendon-bone graft.

FIELD OF THE INVENTION

The present invention is related to the field of bone-tendon-bone graftsand components thereof, for implantation in mammals, particularly forimplantation in humans. More specifically, the present invention isdirected to an intermediate bone block for use in bone-tendon-bone (BTB)grafts wherein the intermediate bone block is capable of being used withthe same or a different bone block to form a bone block assembly thathas an enhanced gripping feature for gripping soft tissue to form anassembled bone-tendon-bone graft suitable for implantation into apatient. The bone-tendon-bone grafts of the present invention are usefulbecause they offer surgeons and patients the advantages of full internaltendon capture, bone to bone contact at the healing interface, use ofany suitable tendon specimen, construction to a predetermined gagelength, and adherence to preferred surgical technique and fixationmethods, while maintaining a significantly increased tensile strengthover BTB grafts formed by stitching, stapling or compression alone.

BACKGROUND OF THE INVENTION

In the field of medicine, there has been an increasing need to developimplant materials for correction of biological defects. Particularly inthe field of orthopedic medicine, there has been the need to replace orcorrect bone, ligament and tendon defects or injuries. As a result,there have emerged a number of synthetic implant materials, includingbut not limited to metallic implant materials and devices, devicescomposed in whole or in part from polymeric substances, as well asallograft, autograft, and xenograft implants. It is generally recognizedthat for implant materials to be acceptable, they must be pathogen free,and must be biologically acceptable. Generally, it is preferable if theimplant materials may be remodeled over time such that autogenous bonereplaces the implant materials. This goal is best achieved by utilizingautograft bone from a first site for implantation into a second site.However, use of autograft materials is attended by the significantdisadvantage that a second site of morbidity must be created to harvestautograft for implantation into a first diseased or injured site. As aresult, allograft and xenograft implants have been given increasingattention in recent years. However, use of such materials has thedisadvantage that human allograft materials are frequently low inavailability and are high in cost of recovery, treatment and preparationfor implantation. By contrast, while xenograft implant materials, suchas bovine bone, may be of ready availability, immunological, regulatoryand disease transmission considerations imply significant constraints onthe ready use of such materials.

In view of the foregoing considerations, it remains the case that therehas been a long felt need for increased supplies of biologicallyacceptable implant materials to replace or correct bone, ligament andtendon defects or injuries. This invention provides a significantadvance in the art, and largely meets this need, by providing materialsand methods for production of various bone-soft tissue implants fromcomponent parts to produce assembled implants.

Orthopedic medicine is increasingly becoming aware of the vast potentialand advantages of using bone/tendon/bone grafts to repair common jointinjuries, such as Anterior Cruciate Ligament (ACL) or Posterior CruciateLigament (PCL) tears. One technique that is currently used for repairingthese types of injuries involves surgically reconnecting the tornportions of a damaged ligament. However, this technique is often notpossible, especially when the damage to the ligament is extensive. Toaddress situations where the damage to the joint ligaments is severe,another technique commonly performed involves redirecting tendons toprovide increased support to a damaged knee. These conventionaltechniques are not without their shortcomings; in most cases, therepaired joint lacks flexibility and stability.

The recent utilization of bone/tendon grafts has dramatically improvedthe results of joint repair in cases of severe trauma. Even in cases ofextensive damage to the joint ligaments, orthopedic surgeons have beenable to achieve 100 percent range of motion and stability using donorbone/tendon grafts. Despite these realized advantages, there have beensome difficulties encountered with utilizing bone/tendon grafts. Forexample, surgical procedures involving transplantation and fixation ofthese grafts can be tedious and lengthy. Currently, bone-tendon-bonegrafts must be specifically shaped for the recipient during surgery,which can require thirty minutes to over an hour of time. Further,surgeons must establish a means of attaching the graft, which also takesup valuable surgery time. Accordingly, there is a need in the art for asystem that addresses this and the foregoing concerns. Thus it is anobject of this invention to provide a BTB that is constructed to precisedimensions and is adapted for robust fixation while allowing adherenceto preferred surgical techniques.

Bone-tendon-bone (BTB) grafts of the prior art are made in one of twoways: (1) by harvesting a naturally occurring tendon/ligament andportions of the bone(s) to which it is attached, thus maintaining thenaturally occurring attachment of tendon/ligament and bone; or (2) byattaching the opposing ends of one or more pieces of tendon, ligament ora synthetic material to separate bone blocks. The name BTB is used forhistorical reasons. One skilled in the art recognizes that bydefinition, a “tendon” is a collagenous cord that attaches muscle to itspoint of origin, typically to bone. By definition, a “ligament” is aband of collagenous tissue that connects bone or supports viscera. Thus,it would appear that a BTB would more properly be called abone-ligament-bone implant. However, many of the earliest BTBs employeda tendon, which is larger and generally more plentiful in a body. Hence,the name BTB became adopted by the art. We have used the term BTB toencompass all of the bone-soft tissue grafts described herein.

Tendons (or ligaments) are fibrous semi-hard materials that are slipperyand difficult to grip. Thus, one of the issues in manufacturing anassembled BTB is how to attach the slippery tendon to the bone. Thetendon has a tendency to squirm and slip when compressed between boneysurfaces, much like a banana peel compressed between the floor and one'sfoot. One solution that is commonly used is to bite the tendon with acomponent that has some sort of teeth or threads, providing improvedgripping over a flat surface. However, teeth or threads have a tendencyto cut into the tendon fibers when the tendon is pulled at high tensilestrength. Thus, most assembled BTBs provide some sort of trade-offbetween reducing slipping and squirming by biting which does not allowfor achievement of maximum tensile strength.

U.S. Pat. No. 5,370,662 (“the '662 patent”), which issued to Stone onDec. 06, 1994 and which is entitled “Suture Anchor Assembly,” disclosesthe use of a screw made from titanium, stainless steel, or some otherdurable, non-degradable, biocompatible material having an eyelet at oneend for attaching a suture connected to a soft material, such as aligament or tendon. U.S. Pat. No. 5,370,662 at col. 1, lines 8-9. Oneproblem with such a device is that the screw, although bio-compatible,will never become assimilated into the patient's body. A second problemis that the tendon or ligament will never form a natural attachment tothe screw.

One attempt at solving these problems was disclosed in U.S. Pat. No.5,951,560 (“the '560 patent”), which issued on Sep. 14, 1999 to Simon etal. and which is entitled “Wedge Orthopedic Screw.” The '560 patentdiscloses a wedge-shaped interference screw made from a biocompatiblematerial for use with a ligament and with two bone blocks for performinganterior cruciate ligament repairs. In the '560 patent, abio-compatible, wedge-shaped interference screw, a bone block and aligament are inserted into an osseous tunnel drilled into a bone of apatient in need of a ligament repair. The interference screw compressesthe flat surface of a bone block against a ligament that is pressed intothe wall of the osseous tunnel. As the interference screw advances, theforce that it presses against the ligament is buttressed by the forceagainst the opposing tunnel wall. A second interference screw compressesa second bone block against an opposing end of the ligament in a secondosseous tunnel drilled in a second bone in need of ligament repair. Itis more difficult to pull a predetermined tension on the tendon becausethe tendon slips in the bone tunnel and uncontrollably alters thetension when the interference screw is being threaded in the bonetunnel. The slippery ligament is also subject to slippage whencompressed between the bone block and the tunnel wall. Such slippageresults in a loss of tension in the joint. In the case of an anteriorcruciate ligament (ACL) repair, this loss of tension causes a wobblyknee. This is undesirable in any human and particularly athletes. It isan object of the present invention to provide a bone to tendonconnection that will decrease slippage and loss of tension in a BTB.Therefore, it is an object of the present invention to provide a BTBwith a stiffness of at least 90N/mm, preferably 170N/mm, more preferably230N/mm. It is also an object of the present invention to provide a BTBwith an elongation of no more than 5 mm, preferably less than 2 mm, morepreferably less than 1 mm. Stiffness and elongation for any given BTBcan be calculated by methods known in the art. Stiffness is defined asthe slope of the force-displacement curve when the BTB is subject toaxial load increasing from below 100 Newtons to above at least 200Newtons. Elongation is defined as the difference in length for a givenBTB measured before the first cycle of a dynamic load test and after1000 cycles of loading to at least 200 Newtons.

Another approach to making a BTB is disclosed in U.S. Pat. No. 5,961,520(“the '520 patent”) which issued to Beck, et al. on Oct. 05, 1999, andwhich is entitled “Endosteal Anchoring Device for Urging a LigamentAgainst a Bone.” Like the '560 patent, the '520 patent utilizes aninterference screw and a bone block (called an “anchor body” therein) topress the end of a ligament against the side wall of an osseous tunnelin the patient's bone. The '520 patent differs from the '560 patent inthat the ligament loops around the bone block in a “U” shape. This “U”shape of the tendon captures the tendon in the first bone tunnel, butleaves two free tendon ends to be secured in the second bone tunnel. Inaddition in the '520 patent, the bone block, which presses the ligamentagainst the walls of the osseous tunnel contains two grooves for“locking” (col. 7, line 2) the ligament in place, and “restrictingexcessive compression on the ligament” (col. 7, lines 8-9). The“locking” of the tendon against the tunnel wall still leaves the tendonfree to move against the tunnel wall near the ends of the anchor body.This leads to impaired healing and recovery due to tendon to bonecontact within the tunnel and also due to micromotions of the tendonwithin the tunnel. Additionally, the location of the tendon in thelocking grooves is a function of the anchor body design and is not acontrolled design parameter. Thus, the tendon placement with respect toeither the tunnel wall or the tunnel centerline cannot be matched toparticular surgical needs or to surgeon preference.

Yet another approach to making a BTB is disclosed in commonly assignedU.S. Pat Appl. Pub. No. 2003/0023304 (“the '304 application”), to Carteret al., which published on Jan. 30, 2003. The '304 application disclosesseveral embodiments of a BTB. In each of the various embodiments, atendon is bound in an internal chamber created in the bone blocks. Forexample, in FIG. 10 a plurality of cams reverse the direction of thetendon several times and cancellous chips packed in any open space biteinto the tendon to keep it from slipping. In FIG. 12, a screw compressesthe tendon against the side of an internal chamber. In FIG. 14, aninternal wedge that has teeth bites into a tendon and tightens the gripas the tendon is pulled. In yet another embodiment, shown in FIG. 15,one end of a tendon is doubled over and the doubled over end is held inplace by a series of grooves and rings. While all of these embodimentsare useful, they each are challenging to manufacture and/or assemble dueto their inherent complexity and reliance on small or intricate parts.It is an object of the present invention to provide a BTB having arobust design, simple components, ease of manufacturability, and highreliability, all while maintaining an acceptable tensile strength,stiffness, and elongation performance. This is important for all BTBgrafts, especially for those implanted in athletes and other individualswhere maximum performance is required.

One isolated and purified BTB that is not hindered by slippage or cutfibers when subjected to high tensile pulling is disclosed in commonlyassigned U.S. Pat. No. 6,497,726 (“the '726 patent”) which issued onDec. 24, 2002 to Carter et al. The '726 patent discloses the use ofnatural BTBs that are cut from allograft or xenograft sources, commonlyreferred to as “pre-shaped BTBs.” Typically, the BTB is cut as a singlepiece from a section of the patella (bone), patellar tendon and thetibia (bone) of the donor. One problem is that only 2-3 grafts can beobtained per knee of the donor, depending upon the donor's age andhealth. Hence, it is an object of the present invention to be able tomake BTB grafts in large quantities. It is also an object of the presentinvention to make BTB grafts having high tensile strength, suitable forACL repairs, from tendon and bone components, wherein the BTBs areconstructed so as to minimize the art recognized slippage and tearingassociated with conventional modes of construction as described above.Another problem with pre-shaped (natural) BTBs is that the size of theBTB or the length of the tendon between the two bone pieces cannot beprecisely selected. Some of the physical dimensions of the graft,particularly tendon (ligament) length, are determined by the anatomy ofthe donor. Frequently, this leads to compromises such as excessive gagelength, or length between the bone blocks, which result in surgicalchallenges and compromised healing and recovery. For example, a naturalBTB with a tendon that is too long for an ACL repair results in having alength of unsecured and wobbling tendon in the bone tunnel between theends of the secured bone portions. The wobbling tendon hinders healingin the bone tunnel. Hence, it is yet another object of the presentinvention to be able to make BTB grafts having a predetermined andvariable set of design parameters including gage length, bone blockdiameter, tendon size, and bone block or tendon shape, size, orientationor a combination thereof.

BRIEF SUMMARY OF THE INVENTION

While engineering an assembled BTB, the Applicants discovered thatinserting one to ten cavities on the compressive surface (i.e., the softtissue engaging surface) of a bone block (hereinafter Applicants'“intermediate bone block”) provides the bone block with an unexpectedlysuperior grip of a tendon (or other soft tissue), relative to boneblocks with untextured (smooth) or textured tissue engaging surfaces. Itis thought that the cavities on the tendon engaging face captureuncompressed tendon (or soft tissue) from above the cavity and theoverflow of adjacent compressed tendon (or soft tissue) allowing thecompressive surfaces of the Applicants' intermediate bone block to graband hold the tendon (or soft tissue) without damaging it, rather thanfloat on it. A preferred cavity is a channel in the tendon (or softtissue) engaging face of the bone block.

The Applicants also discovered that the cross-sectional shape of thecavities, and the layout of the cavities across the soft tissue engagingface of the bone block greatly affected the overall grip on a segment ofsoft tissue sandwiched between the tissue engaging face of Applicants'intermediate bone block and any other bone block. Cavities havecross-sectional profiles that are rectangular, square, semi-circular,semi-ovular, triangular, trapezoidal, sinusoidal, curvilinear, dovetail,omega or a combination thereof. Preferably, the cavity has an omega(“Ω”) shaped cross-section, i.e., is an omega shaped cavity. By the term“omega” shaped cross section is meant that the lateral cross section ofthe cavity that is cut into the face of the intermediate bone block hasthe shape of the Greek letter “Ω”.

These compression surfaces and cavities (i.e., enhanced grippingfeatures) result in a BTB graft that has the advantages of full internaltendon capture and bone to bone contact at the healing interface, andallow the use of any suitable soft tissue (e.g., tendon) specimen,construction to a predetermined gage length, and adherence to preferredsurgical technique and fixation methods, while maintaining asignificantly increased tensile strength over BTBs formed by stitching,stapling or compression alone.

It was also unexpectedly discovered that when the cross-sectional shapeof the cavity (preferably, a channel) was omega shaped, an even moreenhanced gripping of the soft tissue (e.g., tendon) between the opposingfaces of the bone blocks was achieved. It is believed that the undercutshape of the omega cavity allows it to advantageously capture and holdthe uncompressed and overflow soft tissue. Specifically, the omegacavity has a unique shape because it has a narrower mouth than the widthof its cross section due to the fact that the face of the bone block isundercut and the undercut is rounded. This feature allows the softtissue to enter the cavity and expand in a direction opposite to thedirection of the compressed soft tissue immediately above on the tissueengaging surface of the bone block. The rounded profile also greatlyreduces stress concentrations and allows the soft tissue to distributethe compressive load more evenly across the entire cavity. As a result,the omega cavity gently grips the soft tissue without cutting, andprevents it from slipping, sliding or flowing in the direction it isbeing pulled or squeezed. Moreover, unlike the edges of teeth or ridges(see FIGS. 6A-6D) that concentrate force on a tissue at all times duringcompression, the edge of the omega cavity only exerts force when neededin response to the tissue therein being pulled or squeezed. In addition,the narrow mouth of the omega cavity (or channel) on the bone blocksurface provides an additional benefit by maximizing contact (and thusgrip) between the soft tissue (e.g., tendon) and the tissue engagingsurface of the bone block.

The unexpected discovery of the improved performance conferred bychannels, and particularly the undercut channels, and most particularlythe omega channels, represents not only a progression of geometricdesign configuration, but more importantly a transformation in thought:from plain channels cut into the block to incrementally increase area ornumber of contact points, to a new paradigm of engineered cavities thatare carefully designed and controlled to gently grab and hold tissueunder load.

Based upon the above discovery, the present invention has multipleaspects. In its simplest aspect, the present invention is directed to anintermediate bone block comprising a machined segment of cortical bone,cancellous bone, artificial bone or a combination thereof, theintermediate having a soft tissue engaging face comprising one to tencompression surfaces and one to ten cavities, the compression surfacessuitable for compressing soft tissue, the one to ten cavities suitablysized for receiving uncompressed soft tissue and/or the compressed softtissue that is being squeezed from adjacent compression surfaces. Theone to ten cavity(ies) may be holes, pockets, or channels. When thecavities are holes or pockets, they are preferably undercut. Preferably,the one to ten cavity(ies) are channels. It is within the scope of theinvention that the intermediate bone blocks may be made of artificialbone, by which is meant natural or synthetic materials including metals,ceramics polymers, composites or combinations thereof which exhibitproperties similar to cortical bone. Commonly known examples are PolyL-Lactic Acid (PLLA) or calcium phosphate or hydroxyapatite basedmaterials. These are available from various manufacturers such as U.S.Biomaterials, Alachua, Fla. and OsteoBiologics, Inc. (OBI), San Antonio,Tex.

When the one to ten cavities are channels, the channels typically have across-sectional shape that is rectangular, square, semi-circular,semi-ovular, triangular, trapezoidal, sinusoidal, curvilinear, dovetail,omega or a combination thereof, more typically square, rectangular,semi-circular, semi-ovular, dovetailed, or omega-shaped. Preferably, theone to ten channels have an undercut cross-sectional profile. By theterm “undercut” is meant that the cavities open up to be wider thantheir surface opening, much like a doorway opening into a wider room.Two examples of an “undercut cross-sectional profile” are an omega (“Ω”)cross-sectional profile or a blunted triangular cross-sectional profile(like an opening for receiving a dovetail-hereinafter “dovetailed”). Anespecially preferred cavity is a channel, wherein the channel has anomega cross-sectional profile.

The layout of the cavities and/or channels is also within the scope ofthis invention. In its simplest form, the cavity can be a single hole inthe surface of the bone block with an omega shaped sidewall.Alternatively, the cavity can be a pocket or larger hole made byremoving an area of material with an undercut around some or all of theperiphery. When the cavity is a single channel or a plurality ofchannels, the channel(s) can run in the direction of pull of the tendon(FIGS. 12A-12D), or across the direction of pull of the tendon (FIGS.13A-13D), or at an angle to the direction of pull of the tendon (FIGS.16A-16D). In one embodiment of the present invention, the intermediatebone block has two channels with an omega cross-section running in thedirection of pull of the tendon. See FIGS. 11A-11D. It is also withinthe scope of the present invention that one or both ends of the boneblock have the edge of the tendon engaging face reduced. Typically, thisis performed by sanding, routing, grinding or cutting the edge toproduce a round, beveled or chamfered edge. See FIGS. 12A-12D.Preferably, this reduction of the end of the tendon engaging faceresults in an internal leading edge configuration that reduces tissuestresses during assembly and use. It is also within the scope of thepresent invention that the cross-sectional size of the cavities in anylayout be the same (FIGS. 13A-13D) or different (FIGS. 14A-14D). It isadditionally within the scope of this invention for the intermediatebone block to have an overall lengthwise tapering profile. See FIGS.36A-36D.

In other embodiments of the present invention, the layout of thechannels can be such that the channels intersect or cross one another.In FIGS. 15A-15D, a series of channels is shown that criss-cross oneanother to produce a waffle-like pattern on the tendon engaging face ofthe intermediate bone block. In a simpler embodiment, two channelsintersect one another to produce a “V” shaped layout on the tendonengaging face of the intermediate bone block. See FIGS. 16A-16D. Thisembodiment can also be thought of as a single channel that changesdirection much like a bend in the road. It is within the scope of thepresent invention that the layout of channels include a single “V”shape, a plurality of “V” shapes (see FIGS. 16A-16D) or some combinationof different layouts. Channels may be laid out in nested configuration.Other examples of layouts of the channels are “U” shaped, “W” shaped and“A” shaped. Alternative layouts for channels are graphic designs such ascompany insignia, random or psuedo-random designs such as a labyrinth ormaze, or complex mathematically derived patterns such as fractalpatterns.

A preferred layout for the channels is “U” shaped. The “U” shaped layoutincludes a single “U” or 2-10 “Us,” which may be stacked or overlapped.This can also be referred to as nested configuration. Typically, the U′sin the layout are stacked top to bottom. In a preferred embodiment, aset of three “U” channels are stacked top to bottom as shown in FIGS.17A-17D. This layout can be thought of as a variation of the twochannels of FIGS. 11A-11D with the channels being interconnected inthree places. In an especially preferred embodiment, the intermediatebone block of the present invention has a layout on its tendon engagingface of three stacked “U” shaped channels (as shown in FIGS. 17A-17D),each channel having an omega-shaped cross-section. This channelarrangement of three stacked “U” shapes can also be interpreted as adouble stacked “A” shape.

The intermediate bone block has a plurality of uses and can be used witha same or a different bone block to form a plurality of different boneblock assemblies suitable for binding to a soft tissue to form animplantable graft suitable for repair of a defect or injury in the bodyof a mammalian patient. A particularly preferred graft is abone-tendon-bone graft.

In a second aspect, the present invention is directed to a bone blockassembly comprising two components: an intermediate bone block of thepresent invention in combination with a second bone block. The secondbone block can be the same or different than the intermediate bone blockas the advantages of the present invention accrue from Applicants'intermediate bone block having an overflow cavity, as described herein,being present on a single bone block. In the bone block assembly, theintermediate bone block and the second bone block are machined toreceive 1 to 30 biocompatible connectors. As will be discussed laterherein, these biocompatible connectors include any connectors capable ofholding the intermediate bone block and the second bone block (i.e., thebone block assembly) together as a unit.

In a third aspect, the present invention is directed to a bone blockassembly comprising two components: a first intermediate bone block ofthe present invention in combination with 2-10 other bone blocks,providing bone block assemblies containing 3-10 bone blocks. The 2-10other bone blocks can be the same or different than the firstintermediate bone block as the advantages of the present inventionaccrue from an omega cavity being present on a single intermediate boneblock. The 3-10 intermediate bone blocks can have various configurationsfor sandwiching soft tissue. See e.g., FIGS. 27A-D, 28A-D and 29A-D. Inthese bone block assemblies, the intermediate bone blocks are alsomachined to receive 1 to 30 biocompatible connectors.

In a fourth aspect, the present invention is directed to an assembledbone-tendon-bone (BTB) implant comprising a bone block assembly of thepresent invention affixed to one or both ends of a length or a bundle ofsoft tissue. When the assembled BTB of the present invention has a boneblock assembly of the present invention at only one end of the softtissue, the opposing end of soft tissue may be free (e.g., free tendonend) or the bone block at the second and opposing end of the soft tissueis a naturally occurring bone block or portion of bone. Methods forobtaining a tendon that is naturally attached to a block of bone isdisclosed commonly assigned U.S. Pat. No. 6,497,726, entitled “Materialsand methods for improved bone tendon bone transplantation” which issuedon Dec. 24, 2002, and in commonly assigned U.S. Pat. No. 6,805,713,entitled “Materials and methods for improved bone tendon bonetransplantation” which issued on Oct. 19, 2004, both of which areexpressly incorporated herein by reference in relation to theirdisclosure on BTBs and on obtaining a tendon naturally attached to abone block. When the assembled BTB of the present invention has a boneblock assembly of the present invention on each of its ends, the boneblock assemblies may be the same or different. In this embodiment, thesoft tissue is a length of tendon, a bundle of tendons of the same ordifferent lengths, a length of ligament, a bundle of ligaments of thesame length or different lengths, a segment or segments of pericardium,dermis or fascia, or a combination thereof. Preferably, the soft tissueis a length of tendon or ligament or a bundle of tendons or ligaments ofthe same length or different lengths, or a combination thereof. It isalso within the scope of the present invention that the tendons orligaments or both in the bundles be of the same thickness or ofdifferent thicknesses. In the bundles, the tendons, or ligaments or bothare allograft, xenograft, synthetic, artificial ligament scaffolds or acombination thereof. Preferably, the tendons are allograft or xenograft.It is also within the scope of the present invention that theintermediate bone block, the second bone block or both may themselves beindependently constructed from 1 to 30 bone portions, preferably from1-10 bone portions, more preferably from 1 to 5 bone portions, even morepreferably 1 to 3 bone portions, most preferably from 1 to 2 boneportions.

The bone block assemblies of the present invention are affixed to theend of a predetermined length of soft tissue (e.g., tendon) by 1 to 30biocompatible connectors that engage each of the two opposing boneblocks and the tendon that is sandwiched therebetween. Suitablebiocompatible connectors are disclosed herein and include pins that forman interference fit with holes machined in the bone blocks. Typical pinsare made of stainless steel, titanium, or cortical bone. Preferred bonepins are cortical bone pins (i.e., pins made from cortical bone). Thebone block assembly is made by stacking an intermediate bone block ofthe present invention or of the prior art into an assembly fixture (seee.g., FIGS. 33A-33E), then placing a piece of soft tissue into thefixture, followed by a second bone block of the present invention or ofthe prior art. The assembly fixture is then tightened or clamped to holdthe pieces in register while the biocompatible connectors are installed.When the biocompatible connectors are pins, a drill is used to createholes through the assembly, then a reamer cleans and sizes the holes,and finally pins are, pressed into the holes to hold the assemblytogether. The entire assembly is then treated through one or morecleaning or sterilization processes which produces an implantable graftwithout damaging the tissues in the graft. Alternatively, the componentsare be treated individually by an appropriate cleaning or sterilizationprocess prior to assembly. In either case, the optional step of terminalsterilization is performed by methods known in the art such as gamma,e-beam, X-ray, or UV irradiation or by vapor phase hydrogen peroxide, orsupercritical CO₂. Other optional steps include sterile packaging,and/or freezing or freeze drying.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a view of a first comparative bone block-tendon assemblycomprising two bone blocks that sandwich a tendon, each bone blockhaving a smooth tendon engaging surface. FIG. 1 is an exploded view ofthe first comparative bone block assembly. This first comparative boneblock-tendon assembly is tested for average load to failure (Newtons) inTable 1 relative to bone block-tendon assemblies of FIGS. 2A-2B, 3A-3B,4A-4D, 5A-5D, each having at least one different tendon engagingsurface.

FIGS. 2A-2B are views of a second comparative bone block-tendon assemblycomprising two bone blocks that sandwich a tendon, the first bone blockhaving a smooth tendon engaging surface while the second bone block hason its tendon engaging surface a saw-tooth pattern of ridges runningperpendicular to the direction of pull of the tendon and the length ofthe bone block. FIG. 2A is an exploded view of the second comparativebone block assembly. FIG. 2B is a detailed view of the tendon and boneblocks from FIG. 2A. This saw-tooth pattern of ridges is angled toengage the tendon in its direction of pull. (FIG. 6A). This secondcomparative bone block-tendon assembly is tested for average load tofailure (Newtons) in Table 1 relative to bone block-tendon assemblies ofFIGS. 1, 3A-3B, 4A-4D, and 5A-5D, each having at least one differenttendon engaging surface.

FIGS. 3A-3B are views of a third comparative bone block-tendon assemblycomprising two bone blocks that sandwich a tendon, each bone blockhaving a textured (saw-tooth pattern) pattern (FIG. 6A) on its tendonengaging surface. FIG. 3A is an exploded view of the third comparativebone block assembly. FIG. 3B is a detailed view of the tendon and boneblocks from FIG. 3A. This third comparative bone block-tendon assemblyis tested for average load to failure (Newtons) in Table 1 relative tobone block-tendon assemblies of FIGS. 1, 2A-2B, 4A-4D, and 5A-5D, eachhaving at least one different tendon engaging surface.

FIGS. 4A-4D are views of a fourth comparative bone block-tendon assemblycomprising two bone blocks that sandwich a tendon, the first bone blockhaving a textured pattern (saw-tooth pattern of ridges) on its tendonengaging surface (FIG. 6A) while the second bone block is anintermediate bone block of the present invention having an a smoothtendon engaging (compressing) surface that is interrupted by twochannels with rectangular cross-sections running the length of the boneblock, which is in the direction of pull of the tendon. FIG. 4A is anexploded view of the fourth comparative bone block assembly. FIG. 4B isa side view of the assembled fourth comparative bone block assembly.FIG. 4C is an end view FIG. 4D is a detailed view of the tendon and boneblocks from FIG. 4A showing the lengthwise channels having a rectangularcross-section in the intermediate bone block of the present invention.This fourth comparative bone block-tendon assembly was tested foraverage load to failure (Newtons) in Table 1 relative to boneblock-tendon assemblies of FIGS. 1, 2A-2B, 3A-3B and 5A-5D, each havingat least one different tendon engaging surface.

FIGS. 5A-5D are views of a fifth comparative bone block-tendon assemblycomprising two bone blocks that sandwich a tendon, the first bone blockhaving a textured (saw-tooth) pattern of ridges on its tendon engagingsurface (FIG. 6A) while the second bone block is a preferredintermediate bone block of the present invention having an a smoothtendon engaging (compressing) surface that is interrupted by twochannels with omega cross-sections running the length of the bone block(FIG. 1A), which is in the direction of pull of the tendon. FIG. 5A isan exploded view of the fifth comparative bone block assembly. FIG. 5Bis a side view of the assembled fifth comparative bone block assembly.FIG. 5C is an end view FIG. 5D is a detailed view of the tendon and boneblocks from FIG. 5A showing the lengthwise channels having a rectangularcross-section in the intermediate bone block of the present invention.This fifth comparative bone block-tendon assembly was tested for averageload to failure (Newtons) in Table 1 relative to bone block-tendonassemblies of FIGS. 1, 2A-2B, 3A-3B, and 4A-4D, each having at least onedifferent tendon engaging surface.

FIGS. 6A-6D show various views of the textured bone block used in theassemblies of FIGS. 2-5, wherein the texture was a saw-tooth pattern ofridges on the tissue (e.g., tendon) engaging surface. FIG. 6A is aperspective view of the textured bone block. FIG. 6B is a top view ofthe textured bone block looking directly down at the saw-tooth patternof ridges on the (soft) tissue engaging surface. FIG. 6C is a side viewof the textured bone block showing the pattern of ridges appearing fromthis perspective as angled teeth on the tissue engaging surface. FIG. 6Dis a detail view of the saw-tooth pattern as shown on the texturedsurface in FIG. 6C.

FIGS. 7A-7D show various views of another embodiment of a textured boneblock, wherein the texture is a pattern of ridges and valleys on thesoft tissue (e.g., tendon) engaging surface. FIG. 7A is a perspectiveview of the textured bone block. FIG. 7B is a top view of the texturedbone block looking directly down at the pattern. FIG. 7C is a side viewof the textured bone block showing the pattern of ridges and valleys onthe soft tissue (e.g., tendon) engaging surface. FIG. 7D is an end viewof the textured bone block of FIG. 7A.

FIGS. 8A-8D show various views of one embodiment of an intermediate boneblock of the present invention having channels with a square crosssection running across the intended direction of pull (arrow) of asegment of soft tissue (e.g., tendon). FIG. 8A is a perspective view ofthe intermediate bone block. FIG. 8B is a top view of the intermediatebone block looking directly down at the layout (pattern) of channels.FIG. 8C is a side view of the intermediate bone block showing the shapeand pattern of cavities (e.g., channels) and tissue compressingsurfaces. FIG. 8D is an end view of the intermediate bone block of FIG.8A.

FIGS. 9A-9D show various views of one embodiment of an intermediate boneblock of the present invention having channels running across theintended direction of pull (arrow) of a segment of soft tissue (e.g.,tendon). The channels are similar to those in FIGS. 8A-8D except thatthe bottom edges of the channels have a radius (R) edge. FIG. 9A is aperspective view of the intermediate bone block. FIG. 9B is a top viewof the intermediate bone block looking directly down at the pattern ofchannels. FIG. 9C is a side view of the intermediate bone block showingthe pattern of cavities (e.g., channels) and tissue compressingsurfaces. FIG. 9D is an end view of the intermediate bone block of FIG.9A.

FIGS. 10A-10D show various views of another embodiment of anintermediate bone block of the present invention having channels with a“V” shaped cross section running across the intended direction of pull(arrow) of a segment of soft tissue (e.g., tendon). FIG. 10A is aperspective view of the intermediate bone block. FIG. 10B is a top viewof the intermediate bone block looking directly down at the layout(pattern) of channels. FIG. 10C is a side view of the intermediate boneblock showing the pattern of cavities (e.g., channels) and tissuecompressing surfaces. FIG. 10D is an end view of the intermediate boneblock of FIG. 10A.

FIGS. 11A-11D show various views of one embodiment of an intermediatebone block of the present invention having channels with an omega-shapedcross section running substantially in the intended direction of pull(arrow) of a segment of soft tissue (e.g., tendon). FIG. 11A is aperspective view of one embodiment on an intermediate bone block havingchannels with an omega shaped cross section. FIG. 11B is a top view ofthe intermediate bone block looking directly down at the lengthwisepattern of channels. FIG. 11C is a side view of the intermediate boneblock showing the pattern of cavities (e.g., parallel channels) andtissue compressing surfaces. FIG. 11D is an end view of the intermediatebone block of FIG. 11A. If the block of FIG. 11D is rotated 180° in theplane of the paper, the omega shape of channel 117 becomes moreapparent.

FIGS. 12A-12D show various views of another embodiment of anintermediate bone block of the present invention having a layout ofchannels with an omega-shaped cross section running substantially in theintended direction of pull (arrow) of a segment of soft tissue (e.g.,tendon). The intermediate bone block of this embodiment differs fromthat shown in FIGS. 11A-11D because the present embodiment has a brokenedge 128. Preferably, this reduction of the end of the tendon engagingface results in an internal leading edge configuration that reducestissue stresses during assembly and use. FIG. 12A is a perspective viewof one embodiment on an intermediate bone block having channels with anomega-shaped cross section. FIG. 12B is a top view of the intermediatebone block looking directly down at the substantially parallel layout ofchannels. FIG. 12C is a side view of the intermediate bone block showingthe pattern of cavities (e.g., parallel channels) and tissue compressingsurfaces. FIG. 12D is an end view of the intermediate bone block of FIG.12A. If the block of FIG. 12D is rotated 180° in the plane of the paper,the omega shape of channel 127 becomes more apparent.

FIGS. 13A-13D show various views of yet another embodiment of anintermediate bone block of the present invention having a layout ofchannels with an omega-shaped cross section running substantially acrossthe intended direction of pull (arrow) of a segment of soft tissue(e.g., tendon). FIG. 13A is a perspective view of one embodiment on anintermediate bone block having channels with an omega-shaped crosssection. FIG. 13B is a top view of the intermediate bone block lookingdirectly down at the pattern of channels. FIG. 13C is a side view of theintermediate bone block showing the pattern of cavities (e.g., channels)and tissue compressing surfaces. If the block of FIG. 13C is rotated180° in the plane of the paper, the omega shape of channel 137 becomesmore apparent. FIG. 13D is an end view of the intermediate bone block ofFIG. 13A.

FIGS. 14A-14D show various views of yet another embodiment of anintermediate bone block of the present invention having a plurality ofchannels with different sized omega-shaped cross sections runningsubstantially across the intended direction of pull (arrow) of a segmentof soft tissue (e.g., tendon). FIG. 14A is a perspective view of thisembodiment on an intermediate bone block. FIG. 14B is a top view of theintermediate bone block looking directly down at the pattern ofchannels. FIG. 14C is a side view of the intermediate bone block showingthe pattern of cavities (e.g., channels) and tissue compressingsurfaces. If the block of FIG. 14C is rotated 180° in the plane of thepaper, the omega shape of each of different sized channels 147A, 147Band 147C becomes more apparent. FIG. 14D is an end view of theintermediate bone block of FIG. 14A.

FIGS. 15A-15D show various views of yet another embodiment of anintermediate bone block of the present invention having a layout ofchannels with an omega-shaped cross section running substantially acrossthe intended direction of pull (arrow) of a segment of soft tissue(e.g., tendon) and channels with an omega-shaped cross section runningsubstantially in the intended direction of pull (arrow) of a segment ofsoft tissue (e.g., tendon). FIG. 15A is a perspective view of oneembodiment on an intermediate bone block having channels with anomega-shaped cross section. FIG. 15B is a top view of the intermediatebone block looking directly down at the criss-crossing pattern ofchannels. FIG. 15C is a side view of the intermediate bone block showingthe pattern of cavities (e.g., channels) and tissue compressingsurfaces. FIG. 15D is an end view of the intermediate bone block of FIG.15E also showing the omega cross-section of the channels. If the viewsof FIGS. 15C and 15D are rotated 180° in the plane of the paper, theomega cross-sectional shape of channels 157B and 157A, respectivelybecomes more apparent.

FIGS. 16A-16D show various views of yet another embodiment of anintermediate bone block of the present invention having a plurality ofchannels with omega-shaped cross sections running substantially acrossthe intended direction of pull (arrow) of a segment of soft tissue(e.g., tendon). FIG. 16A is a perspective view of this embodiment on anintermediate bone block. FIG. 16B is a top view of the intermediate boneblock looking directly down at the “V” shaped layout of the channels.FIG. 16C is a side view of the intermediate bone block showing thepattern of cavities (e.g., channels) and tissue compressing surfaces. Ifthe block of FIG. 16C is rotated 180° in the plane of the paper, theomega shape of the channels 167 becomes more apparent. FIG. 16D is anend view of the intermediate bone block of FIG. 16A.

FIGS. 17A-17D show various views of a preferred embodiment of anintermediate bone block of the present invention having a plurality ofchannels with omega-shaped cross sections running substantially in theintended direction of pull (arrow) of a segment of soft tissue (e.g.,tendon) and having a component that runs across the direction ofintended pull of the segment of soft tissue. FIG. 17A is a perspectiveview of this embodiment on an intermediate bone block. FIG. 17B is a topview of the intermediate bone block of FIG. 17A looking directly down atthe stacked triple “U” shaped (or double stacked “A”) layout of thechannels. FIG. 17C is a side view of the intermediate bone block showingthe pattern of cavities (e.g., channels) and tissue compressingsurfaces. If the block of FIG. 17C is rotated 180° in the plane of thepaper, the omega shape of the channels 177 becomes more apparent. FIG.17D is an end view of the intermediate bone block of FIG. 17A.

FIGS. 18A-18D show various views of one embodiment of an intermediatebone block of the present invention having channels with an omega-shapedcross section running substantially in the intended direction of pull(arrow) of a segment of soft tissue (e.g., tendon), and having atextured saw tooth pattern of ridges on the tissue engaging surface.FIG. 18A is a perspective view of this embodiment on an intermediatebone block showing the ridges on the soft tissue engaging surface angledto engage the soft issue in the direction of pull. FIG. 18B is a topview of the intermediate bone block looking directly down at the patternof channels. FIG. 18C is a side view of the intermediate bone blockshowing the pattern of cavities (e.g., substantially parallel channels)and tissue compressing surfaces (ridges). FIG. 18D is an end view of theintermediate bone block of FIG. 18A. If the block of FIG. 18D is rotated180° in the plane of the paper, the omega shape of channel 187 becomesmore apparent.

FIGS. 19A-19D show a series of views of the external profile of oneembodiment of an intermediate bone block of the present invention. FIGS.19A-19D are essentially views of the flip side of the intermediate boneblock of FIGS. 11A-11D, respectively, wherein all outside edges wererounded to have a radius. FIG. 19A is a perspective view of oneembodiment of an intermediate bone block wherein each outside edge(i.e., non-soft tissue contacting edge) is a radius edge. FIG. 19B is atop view of the intermediate bone block 190 of FIG. 19A, showing thatall corners are rounded corners of a defined radius. FIG. 19C is a sideview of the bone block 190 of FIG. 19A, showing the radius edge R1 andshowing as a broken line the internal omega shaped channel running thelength of the bone block. FIG. 19D is an end view of the intermediatebone block of FIG. 19A viewed from its end 194 and looking down thelength of the two channels 197 having the omega (“Ω”) shaped crosssection in upright configuration in this perspective.

FIGS. 20A-20D show various views of a semi-capsule shaped embodiment ofan intermediate bone block of the present invention having channels withan omega-shaped cross section running substantially in the intendeddirection of pull (arrow) of a segment of soft tissue (e.g., tendon).FIG. 20A is a perspective view of this embodiment on an intermediatebone block showing holes for receiving a biocompatible pin or otherconnector that would hold the depicted intermediate bone block to anyone of a variety of appropriately shaped opposing bone blocks and asegment of soft tissue sandwiched therebetween. FIG. 20B is a top viewof the soft tissue engaging face of this intermediate bone block lookingdirectly down at the pattern of channels and pin holes. FIG. 20C is aside view of the intermediate bone block showing its semi-capsularshape. FIG. 20D is an end view of the intermediate bone block of FIG.20A. If the block of FIG. 20D is rotated 180° in the plane of the paper,the omega shape of channel 207 becomes more apparent.

FIGS. 21A-21D show various views of the exterior surface of asemi-capsule shaped embodiment of a bone block that can serve as theopposing bone block to the bone block of FIGS. 20A-20D. FIG. 21A is aperspective view of this embodiment of an opposing bone block showingholes for receiving a biocompatible pin or other connector (pin holes)that would hold this bone block to any one of a variety of appropriatelyshaped intermediate bone blocks (of the present invention) and to asegment of soft tissue sandwiched therebetween. FIG. 21B is a top viewof the outside face of this opposing bone block looking directly down atits capsule shape and the position of the pin holes. FIG. 21C is a sideview of the opposing bone block showing its semi-capsular shape. FIG.21D is an end view of the opposing bone block of FIG. 21A. When the boneblock of FIG. 21A has channels on its tissue engaging surface (notshown), it becomes an intermediate bone block of the present invention.

FIGS. 22A-22D show various views of the exterior profile of asemi-capsule shaped embodiment of an intermediate bone block of thepresent invention having channels with an omega-shaped cross sectionrunning substantially in the intended direction of pull (arrow) of asegment of soft tissue (e.g., tendon). In practice, this intermediatebone block may mate with the bone block of FIGS. 20A-20D or FIGS.21A-21D. FIG. 22A is a perspective view of this embodiment on anintermediate bone block showing holes for receiving a biocompatibleconnector (e.g., pin or other connector) that would hold the depictedintermediate bone block to any one of a variety of appropriately shapedopposing bone blocks and a segment of soft tissue sandwichedtherebetween. FIG. 22A also shows that the exterior surface has a curvednotch or groove for maximizing engagement with an interference screw.FIG. 22B is a top view of this intermediate bone block looking directlydown at the groove and pattern of pin holes. FIG. 22C is a side view ofthe intermediate bone block showing its semi-capsular shape. FIG. 22D isan end view of the intermediate bone block of FIG. 22A showing thegroove having a radius R.

FIGS. 23A-23D show views of yet another alternate embodiment for theexterior surface of an intermediate bone block of the invention. FIG.23A is a perspective view of this embodiment of an opposing bone blockshowing holes for receiving a biocompatible connector, e.g., pin orother connector, (pin holes) that would hold this bone block to any oneof a variety of appropriately shaped bone blocks and to a segment ofsoft tissue sandwiched therebetween. Also shown on the exterior surfaceof this embodiment are ridges suitable for gripping the bone tunnel andreducing slippage in the direction of pull (arrow) of the tendon. FIG.23B is a top view of the outside face of this intermediate bone blocklooking directly down at its capsule shape and the position of the pinholes. FIG. 23C is a side view of the opposing bone block showing itssemi-capsular shape. FIG. 23D is an end view of the opposing bone blockof FIG. 23A. In practice, the semi-capsule shaped intermediate boneblock of FIG. 23A can mate with the bone block of FIG. 20A, 21A, 22A orpreferably 23A.

FIGS. 24A-24D are various views of one embodiment of a BTB of thepresent invention. FIG. 24A is a perspective view of one embodiment ofan assembled BTB of the present invention. In this perspective view, theBTB is composed of two assembled bone block assemblies, one on each ofthe opposing ends of a segment of soft tissue. Each bone block assemblyhas at least one intermediate bone block of the present invention as acomponent thereof. FIG. 24B is a top view of the assembled BTB whereinone embodiment for positioning the bone pins is shown. FIG. 24C is aside view of the assembled BTB clearly showing the soft tissue (e.g.,tendon) sandwiched between opposing bone blocks at each end. FIG. 24D isan end view of the assembled BTB clearly showing the soft tissue (e.g.,tendon) sandwiched between opposing bone blocks at each end.

FIGS. 25A-25D are views of another embodiment of a BTB of the presentinvention. FIG. 25A is an exploded perspective view of a preferredembodiment of an assembled BTB of the present invention. In thisexploded perspective view, the BTB is composed of two assembled boneblock assemblies, one on each of the opposing ends of a segment of softtissue. Each bone block assembly has at least one intermediate boneblock of the present invention as a component thereof. FIG. 25B is a topview of the assembled BTB wherein one embodiment for positioning thebone pins is shown. FIG. 25C is a side view of the assembled BTB clearlyshowing the soft tissue (e.g., tendon) sandwiched between opposing boneblocks at each end. FIG. 25D is an end view of the assembled BTB clearlyshowing the soft tissue (e.g., tendon) sandwiched between opposing boneblocks at each end. In this latter view, the bone block-tissue assemblyis generally cylindrical, having the approximate diameter of a bonetunnel into which it can be inserted, and a groove for maximizingcontact with an interference screw.

FIGS. 26A-26D are views of another embodiment of a BTB of the presentinvention. FIG. 26A is a perspective view of another embodiment of anassembled BTB of the invention. In this perspective view, the softtissue (e.g., tendon) is attached to the bone block as in FIG. 24A, butthen each of the bone block assemblies is flipped 180° in the plane ofthe paper such that the segment of soft tissue doubles back over theexterior surface of one of the bone blocks. FIG. 26B is a top view ofthe assembled BTB wherein only the soft tissue is visible FIG. 26C iscross-sectional side view CC of the assembled BTB clearly showing thesoft tissue (e.g., tendon) sandwiched between opposing bone blocks ateach end and the presence of the biocompatible bone pins. FIG. 26D is aside view of the assembled BTB clearly showing the soft tissue (e.g.,tendon) sandwiched between opposing bone blocks at each end.

FIGS. 27A-27D are views of another embodiment of a BTB of the presentinvention. FIG. 27A is a perspective view of the BTB of FIG. 26A furthercomprising a third bone block at each end sandwiching the soft tissuealong the exterior of the bone blocks shown in FIG. 27A to produce a 5layer sandwich assembly at each end comprising layers of bone:softtissue:bone:soft tissue:bone. FIG. 27B is a top view of the assembledBTB wherein the assembly appears the same as in FIG. 24B. FIG. 27C iscross-sectional side view BB of the assembled BTB, clearly showing threebone blocks sandwiching two portions of the length of soft tissue (e.g.,tendon) as those portions in turn sandwich the central bone block. Theassembly is held together at each end by biocompatible pins or otherconnectors. FIG. 27D is a side view of the assembled BTB clearly showingthe soft tissue (e.g., tendon) sandwiched between opposing bone blocksat each end.

FIGS. 28A-28D are views of another embodiment of a BTB of the presentinvention comprising a 5 layer assembly at each end. FIG. 28A is aperspective view of a double tendon BTB comprising layers of bone:softtissue:bone:soft tissue:bone. FIG. 28B is a top view of the assembledBTB wherein the assembly appears the same as in FIG. 24B. FIG. 28C is aside view of the assembled BTB, clearly showing three bone blockssandwiching two distinct lengths of soft tissue (e.g., tendon) as thoseportions in turn sandwich the central bone block. The assembly is heldtogether at each end by biocompatible pins or other connectors. FIG. 28Dis an end view of the BTB of FIG. 28A.

FIGS. 29A-29D are views of a dual tendon BTB that is a hybrid of FIGS.28A and 24A insofar as the bone-tendon assembly at one end is a threelayer sandwich and at the opposing end is a five layer sandwich. FIG.29A is a perspective view of a double tendon BTB comprising 5 layers(bone:soft tissue:bone:soft tissue:bone) at one end and 3 layers(bone:soft tissue:bone) at the opposing end. FIG. 29B is a top view ofthe assembled BTB wherein the assembly appears substantially the same asin FIG. 24B. FIG. 29C is a side view of the assembled BTB, clearlyshowing three bone blocks sandwiching two distinct lengths of softtissue (e.g., tendon) at one end and two bone blocks sandwiching asingle length of soft tissue at the opposing end. The assembly isoptionally held together at each end by 2-3 biocompatible connectors,e.g., pins or other mechanical connectors. FIG. 29D is an end view ofthe BTB of FIG. 29A.

FIGS. 30A-30B are side and end views, respectively, of a harvested BTB300 having a tendon 303 of a first defined length L1 naturally attachedat its first end to a first bone block and naturally attached at itssecond end to a second bone block. FIGS. 30C and 30D are side and endviews, respectively, of 2 spacers for reducing the first defined lengthL1 of tendon 303 to a shorter functional length L2, and optionally, 2bone blocks for capping the tendon and providing for greater bone tobone contact between the graft and the a bone tunnel in a patient. FIGS.30E and 30F are side and end views, respectively, of an assembled boneblock wherein the length L1 of the tendon in a harvested BTB has beenreduced to L2 by assembling a spacer and an intermediate bone block ofthe invention to each of the naturally attached bone blocks.

FIGS. 31A-31D are views of an alternate embodiment of an intermediatebone block of the present invention. FIG. 31A is a perspective view ofone embodiment on an intermediate bone block having a sloped channel ofuniform width. FIG. 31B is a top view of the intermediate bone blocklooking directly down at the central sloped channel. FIG. 31C is a sideview of the intermediate bone block showing the slope of the centralchannel. FIG. 31D is an end view of the intermediate bone block of FIG.31A looking up the sloping channel.

FIGS. 32A-32D are views of an alternate embodiment of an intermediatebone block of the present invention. FIG. 32A is a perspective view ofone embodiment on an intermediate bone block having a converging channelof substantially uniform depth. FIG. 31B is a top view of theintermediate bone block showing the channel converging from the opposingend. FIG. 31C is a side view of the intermediate bone block showing thatthe channel is of a substantially uniform depth. FIG. 31D is an end viewof the intermediate bone block of FIG. 31A looking toward the convergingchannel at the opposing end.

FIGS. 33A-33E are views of a template (jig or assembly fixture) used toassemble one end of a BTB (i.e., a bone block-tendon assembly). FIG. 33Ais an exploded view of the template showing the upper and lower halves,the locking screws, and the holes for positioning the interference pinsprior to impaling them into the templated bone:tendon:bone sandwichlocked in position below. FIG. 33B is a perspective view of theassembled template which in this locked position would place a standardamount of tension on the pre-sized bone blocks and soft tissue placedtherein prior to insertion of the interference pins. FIG. 33C is a topview of the assembled template. FIG. 33D is a front view of theassembled template showing opening 339 where the segment of soft tissue(e.g., tendon) would extend outside the device. FIG. 33E is a side viewof the assembled template.

FIGS. 34A-34D provide views of another embodiment of an assembled BTB ofthe present invention wherein a single segment of soft tissue (e.g.,tendon or ligament) is doubled back to provide a double tendon BTB. FIG.34A is a perspective view of the assembled BTB of this invention havingan intermediate bone block 344 of the present invention sandwiching atendon between an opposing bone block 346. FIG. 34B is a top view of theBTB where the biocompatible connectors in the top of the opposing boneblock are clearly visible. FIG. 34C is a side view showing tendon 343doubling back on itself. FIG. 34D is view of the proximal end of the BTBin FIG. 34A, showing the bone blocks sandwiching the doubled up tendon.

FIGS. 35A-35D provide views of another embodiment of an assembled BTB ofthe present invention wherein a single segment of soft tissue (e.g.,tendon or ligament) is doubled back to provided a double tendon BTB.This embodiment is a variation of the embodiment of FIG. 34 but furtherincludes two additional bone blocks at the two tendon end to sandwichthe tendon and provide for bone to bone contact between the graft andthe patient's bone when the graft is implanted in the surgically excisedbone tunnel in the patient. FIG. 35A is a perspective view of theassembled BTB of this invention having an intermediate bone block 354 ofthe present invention sandwiching a tendon between an opposing boneblock 356. FIG. 35B is a top view of the BTB where the biocompatibleconnectors in the top of the opposing bone block-tendon assemblies areclearly visible. FIG. 35C is a side view showing tendon 353 doublingback on itself. FIG. 35D is an end view of the BTB at the end where thetwo bone blocks sandwich the doubled up tendon.

FIGS. 36A-36D are a series of views of another embodiment of anassembled BTB of the present invention. FIG. 36A is a perspective viewof an assembled BTB comprising a length of soft tissue having opposingfirst and second ends, wherein the first and second ends, respectively,of the soft tissue are separately sandwiched between wedge shapedopposing bone blocks, the angle of the wedges being such that incombination, the wedges form a 3 dimensional shape whose opposinglongitudinal surfaces are substantially parallel. Thus, the opposingfaces of the bone blocks contain a lengthwise tapering profile. FIG. 36Bis a top view of this embodiment of assembled BTB. FIG. 36C is a sideview of this embodiment of assembled BTB showing the assembly detailsand the use of suitable biocompatible connectors. FIG. 36D is an endview of the proximal end of the assembled BTB as positioned in FIG. 36A.

The foregoing summary, as well as the following detailed description ofcertain embodiments of the present invention, will be better understoodwhen read in conjunction with the appended drawings. For the purpose ofillustrating the invention, there is shown in the drawings, certainembodiments. It should be understood, however, that the presentinvention is not limited to the arrangements and instrumentality shownin the attached drawings.

DETAILED DESCRIPTION OF THE INVENTION

The present invention has multiple aspects. In its simplest aspect, thepresent invention is directed to an intermediate bone block comprising amachined segment of cortical bone, cancellous bone, artificial bone or acombination thereof, the intermediate bone block having a facecomprising one to ten compression surfaces and one to ten cavities, thecompression surfaces suitable for compressing soft tissue, the one toten cavities suitably sized for receiving uncompressed soft tissueand/or the compressed soft tissue that is being squeezed from adjacentcompression surfaces. Preferably, the bone block is cortical bone orcancellous bone or a combination thereof. More preferably, the boneblock is cortical bone. While engineering an assembled BTB, theApplicants discovered that combining the compressive surfaces of a boneblock with one to ten cavities on the tendon engaging surface of a thebone block, allows the uncompressed soft tissue and the overflow of thecompressed soft tissue to flow into the cavities. The Applicantsdiscovered that both the presence of the cavities on the tendon engagingfaces of the bone blocks and the cross-sectional shape and layout of thecavities contributed to the overall grip of the bone blocks to the softtissue sandwiched between tendon engaging faces of independent opposingbone blocks.

The cavities are preferentially channels cut into the tendon engagingface of the bone blocks. Applicants discovered that the channelsunexpectedly increase the grip of the tendon between the bone blocks. Itis thought that the cavities (preferably, channels) capture uncompressedsoft tissue (e.g., tendon) and the overflow of the adjacent compressedtissue allowing the compressive surfaces of the bone block to grab andhold the tissue rather than float on it. It was unexpectedly discoveredthat when the cross-sectional shape of the cavities is an omega shape,the maximum gripping of the tendon between the opposing bone blocks isachieved. It is believed that the omega shaped cross sectionadvantageously captures and holds the uncompressed and overflow softtissue. Specifically, the omega shaped cavity (preferably, channel) hasa narrower mouth than the body of the cavity (channel) because thetendon engaging face of the bone block is undercut. This feature allowsthe soft tissue to enter the cavity and expand in a direction oppositeto the direction of the compressed soft tissue immediately above on thesurface of the bone block. The rounded omega profile also eliminatesstress concentrations and allows the soft tissue to expand anddistribute the compressive load evenly across the entire cavity. Thiscontrolled expansion and even distribution of load occurs withoutcompromising the internal structure and related natural properties ofthe soft tissue. As a result, the omega cavity gently grips the softtissue without cutting, and prevents it from slipping, sliding orflowing in the direction it is being pulled or squeezed. Moreover,unlike teeth, the edge of the omega cavity only exerts force when neededin response to being pulled or squeezed. In addition, the narrow mouthof the omega cavity (or channel) on the bone block surface maximizescontact between the bone block surface (tendon engaging surface) and thetendon, and thus maximizes grip.

In a preferred intermediate bone block of the present invention, the oneto ten cavity(ies) have an undercut cross-sectional profile. By the term“undercut” is meant that the cavities open up to be wider than theirsurface opening, much like a doorway opening into a wider room. Twoexamples of an “undercut cross-sectional profile” are an omegacross-sectional profile or a blunted triangular cross-sectional profile(like an opening for receiving a dovetail). An preferred cavity is achannel, more preferably a channel with an undercut profile, mostpreferably, a channel that has an omega cross-sectional profile.

The intermediate bone block of the present invention has a plurality ofuses and can be used with an identical bone block, a different boneblock of the present invention, or a bone block of the prior art, toenhance the grip upon any soft tissue that engages its soft tissue(e.g., tendon) engaging surface. Thus, the intermediate bone block ofthe present invention is a versatile and functional component that canbe combined with other components to form a plurality of different boneblock assemblies suitable for binding to a soft tissue to form animplantable graft suitable for repair of a defect or injury in the bodyof a mammalian patient. A particularly preferred graft is abone-tendon-bone graft. This graft is described in more detail below.

By the term “mammalian” patients is meant humans, domesticated animalsand zoological specimens. Typical domesticated mammals are dogs, cats,horses, goats, sheep, pigs, llamas, and cattle. The bone source for theintermediate bone block of the present invention is autograft,allograft, xenograft, or artificial bone. However, because theintermediate bone block is machined, it is typically allograft,xenograft, or artificial bone. Preferably, the bone source is allograftor xenograft bone. When the recipient patient is a human, the bonesource is preferably human allograft bone. Due to constraints of humanallograft availability and current advances in the use and processing ofxenografts, there are also some cases where the bone source ispreferably xenograft bone, and more preferably xenograft bone treated toreduce antigenicity and immune response.

The soft tissue is typically a collagenous material that is autograft,allograft or xenograft. Alternatively, the soft tissue may be a naturalor synthetic material. Preferably, the soft tissue is a predeterminedlength of tendon, a bundle of tendons of the same or different lengths,a predetermined length of ligament, a bundle of ligaments of the samelength or different lengths, a segment or segments of pericardium,dermis, fascia, dura, skin, submucosal tissue (e.g., intestinal tissue),cartilage, or a combination thereof. Typically, the source of the softtissue is autograft, allograft, or xenograft. Most typically, the sourceof the soft tissue is allograft or xenograft. When the recipient patientis a human, the source is preferably human allograft. However, in somesituations, particularly in tendon repair, a tendon bundle comprising axenograft tendon bundle or a combination of allograft and xenografttendons of different thicknesses and lengths, provides for enhancedperformance under extreme stresses. This combination is discussedfurther herein in relation to an assembled bone-tendon-bone implant ofthe present invention

To make an omega-shaped cavity, the surface is undercut with a ball millto produce a cavity that has a greater interior width than the surfaceopening. The cavities with the omega cross section preferably run as oneor more independent or intersecting channels on the soft tissue engagingsurface of the intermediate bone block. See FIGS. 11-18. In oneembodiment, the layout of one or more of the channels across the softtissue-engaging surface is linear across the face of the intermediatebone block. See FIGS. 11A-11D. In another embodiment, one or more of thechannels is laid out to form a “V”-shaped channel (when viewed fromabove) across the soft tissue-engaging surface of the intermediate boneblock. See FIGS. 16A-16D. In yet another embodiment, the layout ofchannels can form a series of “V”s across the soft tissue-engagingsurface. In yet another embodiment, one of the omega channels is laidout as a W-shaped channel (when viewed from above) across thetissue-engaging surface of the intermediate bone block. The omega crosssection can be made by precision milling parallel to the surface of theintermediate bone block with a ball shaped end mill, such that the toolremoves some of the surface bone but primarily undercuts bone just belowthe surface. Such a tool is available from Dremel, Racine Wis. Anothermeans for making the omega cross section is to use a router and theappropriate bit or bits. Because a router can be easily templated toswitch directions, it is most convenient for laying out channels thatswitch directions across the face of the bone block, such as the “A,”“U,” “V” and “W” layout of channels having an omega cross section.

In a second aspect, the present invention is directed to a bone blockassembly comprising an intermediate bone block of the present inventionin combination with a second bone block. The second bone block can bethe same or different than the intermediate bone block as the advantagesof the present invention accrue from Applicants' intermediate bone blockhaving an overflow cavity, as described herein, being present on asingle bone block. In the bone block assembly, the intermediate boneblock and the second bone block are machined to receive 1 to 30biocompatible connectors. As will be discussed later herein, thesebiocompatible connectors include any connectors capable of holding theintermediate bone block and the second bone block (i.e., the bone blockassembly) together as a unit.

In a third aspect, the present invention is directed to a bone blockassembly comprising a first intermediate bone block of the presentinvention in combination with 2-10 other bone blocks, providing boneblock assemblies containing 3-10 bone blocks. The 2-10 other bone blockscan be the same or different than the first intermediate bone block asthe advantages of the present invention accrue from an omega cavitybeing present on a single intermediate bone block. The 3-10 intermediatebone blocks can have various configurations for sandwiching soft tissue.See e.g. FIGS. 27, 28 and 29. In these bone block assemblies, theintermediate bone blocks are also machined to receive 1 to 30biocompatible connectors.

In a fourth aspect, the present invention is directed to an assembledbone-tendon-bone (BTB) implant comprising a bone block assembly of thepresent invention affixed to one or both ends of a length or a bundle ofsoft tissue. When the assembled BTB of the present invention has a boneblock assembly of the present invention at only one end of the softtissue, the opposing end of soft tissue may be free (e.g., free tendonend) or the bone block at the second and opposing end of the soft tissueis a naturally occurring bone block or portion of bone. Methods forobtaining a tendon that is naturally attached to a block of bone isdisclosed commonly assigned U.S. Pat. No. 6,497,726, entitled “Materialsand methods for improved bone tendon bone transplantation” which issuedon Dec. 24, 2002, and in commonly assigned U.S. Pat. No. 6,805,713,entitled “Materials and methods for improved bone tendon bonetransplantation” which issued on Oct. 19, 2004, both of which areexpressly incorporated herein by reference in relation to theirdisclosure on BTBs and on obtaining a tendon naturally attached to abone block. When the assembled BTB of the present invention has a boneblock assembly of the present invention on each of its ends, the boneblock assemblies may be the same or different. In this embodiment, thesoft tissue is a length of tendon, a bundle of tendons of the same ordifferent lengths, a length of ligament, a bundle of ligaments of thesame length or different lengths, a segment or segments of pericardium,dermis or fascia, or a combination thereof. Preferably, the soft tissueis a length of tendon or ligament or a bundle of tendons or ligaments ofthe same length or different lengths, or a combination thereof. It isalso within the scope of the present invention that the tendons orligaments or both in the bundles be of the same thickness or ofdifferent thicknesses. In the bundles, the tendons, or ligaments or bothare allograft, xenograft, synthetic, artificial ligament scaffolds or acombination thereof. Preferably, the tendons are allograft or xenograft.It is also within the scope of the present invention that theintermediate bone block, the second bone block or both may themselves beindependently constructed from 1 to 30 bone portions, preferably from1-10 bone portions, more preferably from 1 to 5 bone portions, even morepreferably 1 to 3 bone portions, most preferably from 1 to 2 boneportions.

As used herein, the “T” component of the BTB is intended to refer to alength of tendon, a bundle of tendons of the same or different lengths,a length of ligament, a bundle of ligaments of the same length ordifferent lengths, a segment or segments of pericardium, dermis, fascia,dura, skin, submucosal tissue (e.g. intestinal tissue), cartilage, or acombination thereof. Bundles refer to 1-10 discrete tendons orligaments, which themselves can be made up of smaller fibers oftendons/ligaments that are stapled, glued, sutured, woven or braided.Alternatively, tendons or other soft tissues are crosslinked with acrosslinking agent. In another alternate embodiment, the segment of softtissue is sufficiently large so that excess tissue extends beyond theend or sides of the bone block assembly. This excess soft tissue isuseful for surgical placement and/or fixation. As used herein, the “T”component or the BTB may also contemplate an engineered construct ofnatural or synthetic origin, such as a synthetic ligament repairscaffold, other flexible synthetic biomaterial, or specially formulatednatural material such as that disclosed in the applicant's copendingapplications U.S. Ser. No. 10/754,310, entitled “Matrix Composition ForHuman Grafts/Implants” and filed Jan. 09, 2004, and in U.S. Ser. No.10/793,976, entitled “Muscle-Based Grafts/Implants” and filed Mar. 05,2004. Engineered constructs include, for example, processedcollagen-based tissue matrix, such as the product sold under the tradename GraftJacket®, by Wright Medical Technology, Inc., Arlington, Tenn.

When the assembled BTB of the present invention has a bone blockassembly of the present invention on the opposing ends of the softtissue, the bone block assemblies may be the same or different. In thisembodiment, the soft tissue is a length of tendon, a bundle of tendonsof the same or different lengths, a length of ligament, a bundle ofligaments of the same length or different lengths, a segment or segmentsof pericardium, dermis, fascia, dura, skin, submucosal tissue (e.g.intestinal tissue), cartilage, or a combination thereof. Preferably, thesoft tissue is a length of tendon or ligament or a bundle of tendons orligaments of the same length or different lengths, or a combinationthereof.

By selecting a bundle of tendons or ligaments of different length, or acombination thereof, the assembled BTB of the present invention can betailored to the needs of the patient. For example, when two of theshorter ligaments stretch under strain to the length of one or morelonger ligaments, the restraint posed by the longer ligaments engagesand acts to stabilize the joint. See, e.g., FIG. 28A-D. By having a BTBwith two to four lengths of ligament, tendon or a combination thereof, areconstructed tendon can have multiple fall back positions to stabilizea joint. This effect can also be achieved by utilizing assemblies thatcontain 3 or more bone blocks. See, e.g., FIGS. 28A-D & 29A-D.Alternatively, multiple tendons can be designed to have multiple pointsof attachment or rotation, mimicking the structure and function of themulti-bundled native anterior cruciate ligament (ACL) construct. Suchconstruction is particularly useful for anterior cruciate reconstructionin a human knee joint. By varying the number and length of ligaments ortendons in a bundle, an assortment of BTBs can be made that would becustomized and suitable for a range of patients from the 65-year-oldrecreational shuffleboard enthusiast to the 25 year old starprofessional football running back.

It is also within the scope of the present invention that the tendons orligaments or both in the bundles are of the same cross-sectional area orof different cross-sectional area. In the bundles, the tendons, orligaments or both are allograft, xenograft or a combination thereof.Preferably, the tendons are allograft.

Additionally, in some cases an entire BTB comprising a combination ofallograft, xenograft, synthetic or artificial tissues offers advantagesin strength, fixation, mechanical properties, biochemical properties,healing, design freedom and/or availability. In one embodiment, a BTB isconstructed of synthetic or allograft or autograft tendon, with axenograft bone block assembly at one or both ends. In anotherembodiment, a BTB is constructed of artificial or allograft bone withxenograft tendons. In yet another embodiment, an allograft tendon isattached to a conventional bone block by a naturally occurringattachment at one end, and attached to a xenograft or artificial boneblock assembly at the other end. In yet another embodiment, acombination of allograft and xenograft tendons is assembled with acombination of allograft or xengraft or synthetic bone blocks.

Finally, it is also within the scope of the present invention that theintermediate bone block, the second bone block or both are independentlyconstructed or assembled from 1 to 30 bone portions, preferably from1-10 bone portions, more preferably from 1 to 5 bone portions, even morepreferably from 1 to 3 bone portions, most preferably from 1 to 2 boneportions. The bone portions are cortical bone, cancellous bone,artificial bone or a combination thereof. Preferably, the bone blockportions are cortical bone, cancellous bone or a combination thereof.More preferably, the bone block portions are cortical bone. Typically, amajority of the bone portions are cortical bone.

By way of example, 30 planks of cortical bone 1 mm in width are stackedright to left with their ends in the direction of pull of the tendon.With the planks being held in juxtaposition to one another, from 2 to 10through holes of a predetermined diameter are precision drilled acrossthe width of the 30 stacked planks. Typically, the width of the throughholes is from about 1 mm to about 2 mm. Into each of the through holesis then inserted an appropriately shaped biocompatible connector thathas an interference fit with the through-hole

As noted above, the bone block assemblies of the present invention areaffixed to the end of a predetermined length of soft tissue (e.g.,tendon) by 1 to 30 biocompatible connectors that engage each of the twoopposing bone blocks and the tendon that is sandwiched therebetween. Theterm “biocompatible connector” includes but is not limited to a pin,screw, suture, staple, rivet, strap, nail, band, adhesive, or chemicalcross linker. The biocompatible connector may be made from: metal,polymer, bone or other biologics including connective tissues. It isunderstood that when discussing sutures, adhesives, cross linkers, andother continuous or non-unitary biocompatible connectors, that a singleapplication of the biocompatible connector type may contain multiplesmaller units. For example, a single suture connection can be fabricatedby stitching a plurality of sutures, e.g., 10 to 100 small individualsutures, and a single adhesive connection may be made by applying aplurality of drops of adhesive, e.g., 10 to 100 small individual dropsof adhesive. A suitable biocompatible connector is pin that is pressfitted into a hole machined in the bone block. A typical pin is madefrom stainless steel, titanium, or cortical bone. A preferred pin is acortical bone pin (i.e., a pin made from cortical bone). Interferencefit cortical bone pins are preferred over the alternative biocompatibleconnector types listed above because they offer a strong and predictablefixation, are readily manufactured, incorporate and heal into the body,are simple to assemble, integrate easily into most graft designs andhave minimal regulatory or safety risks.

It is desirable to have a tight and accurate interference fit betweenthe pin(s) and the hole(s) in bone pieces that are connected by thepin(s). The target range for the pin in such an interference fit is0.001 inches (0.0254 mm) to 0.003 inches (0.0762 mm) larger than thehole diameter, and is pressed fit into place. However, when the pin ismade from cortical bone, it has been learned that freeze-drying the bonepins and other bone pieces exerts a disproportionate shrinkage upon thepins compared to the hole diameters. That is, the pin shrinks slightlymore than the hole shrinks. Uncorrected, this would result in a lessaccurate, and less acceptable, interference fit.

The following method can to solve this problem. A bone pin, preferablyof cortical bone, of a desired diameter is vacuum dried for at leastfive hours. This drying is preferably at room temperature and at anegative pressure of approximately 100 milliTorre. This pre-treatmentresults in a shrinkage of approximately 80 percent of the totalshrinkage that would occur in freeze drying. The pin diameter ismeasured, and a hole is made in the portions to be assembled using anappropriately sized drill bit. The target size for the hole is 0.002inches (0.0508 mm) to 0.0025 inches (0.0635 mm) smaller than thepost-vacuum-drying pin diameter. Preferably, prior to this drilling, thebone portions to be assembled have been kept saturated with moisture tomaintain a consistent size and subsequent shrinkage percent. After allholes are drilled, the pin(s) are press fitted into the through holes,machined into an intermediate bone block of the present invention (orinto a second bone block), and then freeze dried. The resultingassembled allografts have been found to have interference fits in thedesired target range. This method is applicable to the variousembodiments described in this disclosure. Where the bone pins are notfreeze dried, it is sufficient to dip them in alcohol to facilitatetheir insertion (press fitting).

To be suitable for implantation in humans, the bone block and softtissue of the present invention must be treated to remove any antigenicproteins, which may generate a rejection of the implant. It also must betreated to remove any bacteria and viruses. Suitable processes forremoving antigenic proteins and sterilizing to neutralize any bacteriaand viruses are known in the art. See U.S. Pat. No. 5,846,484, entitled“Pressure flow system and method for treating a fluid permeableworkpiece such as a bone,” which issued to Scarborough, et al. on Dec.8, 1998. In the present case, the applicants utilized the assignees'well known method for defatting tissue, which also has the added benefitof removing blood, cellular debris, and soluble and antigenic proteins,by subjecting the muscle tissue to alternating cycles of pressure andvacuum in the sequential presence of solvents, such as isopropylalcohol, hydrogen peroxide and a detergent. These assignee's processesalso neutralize any bacteria and viruses. These processes are disclosedin full detail in assignee's U.S. Pat. No. 6,613,278, entitled “TissuePooling Process,” which issued to Mills et al., on Sep. 02, 2003; U.S.Pat. No. 6,482,584, entitled “Cyclic implant perfusion cleaning andpassivation process,” which issued to Mills, et al. on Nov. 19, 2002;and U.S. Pat. No. 6,652,818, entitled “Implant Sterilization Apparatus,”which issued to Mills et al., on Nov. 25, 2003, all of which areincorporated herein by reference in their entirety.

An improved process for cleansing (treating) soft tissues (and bone) forimplantation, while preserving the desirable traits of flexibility andstrength in the soft tissue, is disclosed in commonly assigned U.S.patent application Ser. No. 10/828,653, entitled “Process and Apparatusfor Treating Implants Comprising Soft Tissue,” in the name of Mills etal., filed Apr. 20, 2004, which is hereby incorporated by reference forits disclosure on such process for cleansing.

The various aspects of the present invention can best be understood byreference to the drawings. FIGS. 1, 2A-B, 3A-B, 4A-D and 5A-D providecomparative drawings of the bone-block tendon assemblies (BTAs) thatwere tested in triplicate (n=3) for average (mean) load to failure inNewtons as reported in Table 1.

TABLE 1 FIG. No. showing Description of the tendon the Bone engagingsurfaces of the two Average Load to Failure block-Tendon Bone Blocks ofthe Bone Newtons assembly Block-Tendon Assembly (n = 3) 1 Flat-Flat 260N 2 Flat-Textured* 344 N 3 Textured-Textured 343 N 4Textured-Rectangular 426 N Channels 5 Textured-Omega Channels 516 N *Inall these examples, textured means texture was provided by a saw-toothpattern.

In Table 1, load to failure was the average of three measurements madeon an Instron model 5800 force testing machine, Instron, Canton, Mass.and reflects the amount of force at which the bone lock tendon assembly(BTA) failed to retain the tendon when the tendon was pulled oppositethe direction of the bone block. In Table 1, a bone block of each of theBTAs of FIGS. 1-5 differed from the prior BTA in the Table solely in thecharacteristics of one of the tendon engaging surfaces of the two boneblocks that sandwiched the tendon therebetween. In Table 1, the BTA ofFIG. 1 had two bone blocks wherein each had a smooth tendon engagingsurface. The BTA of FIG. 2A had one bone block with a smooth tendonengaging surface and a second bone block with a tendon engaging surface(FIG. 6A) that was textured with a saw tooth pattern (0.030 inch, or0.76 mm teeth) that gripped opposite the direction of pull of thetendon. The BTA of FIG. 3A had both a first bone block and a second boneblock each of which had a tendon engaging surface (FIG. 6A) that wastextured with a saw tooth pattern (0.76 mm teeth) that gripped oppositethe direction of pull of the tendon. The BTA of FIG. 4 had one boneblock with a tendon engaging surface of the present invention (i.e.,having a channel with a cavity with a rectangular cross-sectional areathat ran in the direction of pull of the tendon) and a second bone blockwith a tendon engaging surface (FIG. 6A) that was textured with a sawtooth pattern (0.76 mm teeth) that gripped opposite the direction ofpull of the tendon. Finally, the BTA of FIGS. 5A-D had one bone blockwith a tendon engaging surface (FIG. 11A) of the present invention(i.e., having a channel with an omega cavity that ran in the directionof pull of the tendon) and a second bone block with a tendon engagingsurface (FIG. 6A) that was textured with a saw tooth pattern (0.76 mmteeth) that gripped opposite the direction of pull of the tendon.

As reflected in Table 1, the BTA of FIG. 1 with the two opposing smoothtendon engaging surfaces exhibited failure under the lowest load of 260N (n=3). When one of the bone blocks with the smooth tendon engagingsurfaces of FIG. 1 was substituted with a bone block having a frictionalengaging surface (i.e., having saw teeth) to produce the BTA of FIG. 2,the average load to failure of the BTA increased by 84 N to 344 N (n=3).However, substituting a second frictional engaging surface having sawteeth for the smooth bone block of FIG. 2 to produce the BTA of FIG. 3did not produce any incremental gain in average load to failure, i.e.,average load to failure remained essentially the same as the BTA of FIG.2 at 343 N (n=3). However, when one of the frictional engaging surfacesof the BTA of FIG. 3 was substituted with an intermediate bone block ofthe present invention having a smooth surface that was interrupted bytwo channels having a rectangular cross-section to produce the BTA ofFIG. 4, the average load to failure of the resulting BTA unexpectedlyincreased by 83 N to 426 N (n=3). When the same frictional engagingsurfaces of the BTA of FIG. 3 was substituted with an intermediate boneblock of the present invention having a smooth surface that wasinterrupted by two channels having an omega-shaped cross-section toproduce the BTA of FIG. 4, the average load to failure of the resultingBTA unexpectedly increased by 173 N to 516 N (n=3).

Table 2 is compares the mean load to failure of five bone tendonassemblies as a function of the layout or configuration of channels(having an omega cross section) in five intermediate bone blocks of thepresent invention.

TABLE 2 Area of Percent Compression Compression Percent Mean SurfaceSurface Volume Volume Load to Remaining Remaining Removed RemovedFailure Filename Description (mm²)¹ (%) (mm³) (%) (N) design01 Double“1” layout 194.8 77.9 137.0 30.4 506 e.g. FIG. 12A design02 Inverted “U”layout 190.7 76.3 147.2 32.7 520 design03 Inverted big “U” layout 166.866.7 187.5 41.7 528 design04 “A” shaped layout 149.6 59.8 217.0 48.2 560design05 Double “A” layout 129.5 51.8 251.9 56.0 565 e.g. FIG. 17A ¹Theoriginal area of the compression surface of the uncut block is 10 mm ×25 mm = 250 mm².

Separately, Table 2 compares the mean load to failure of the variouslayouts as a function of the volume (mm³) of bone block removed bycreation of the channels. In generating the data for Table 2, each ofdesigns 01-05 was cut into the same size (10 mm×5 mm×25 mm) corticalbone block. The omega channels were cut with a 2.4 mm diameter ball endcutter, to a depth of 1.8 mm. The values for % Volume Removed werecalculated based on the percentage of the machinable volume cut away, inthis case defined by the maximum machinable depth of 1.8 mm. Theopposing (cortical) bone blocks that were opposite each of designs 01-05were substantially identical (to within manufacturing tolerances) andwere the same length (25 mm), width (10 mm) and thickness (5 mm) as thebone blocks of designs 01-05. Each of the opposing bone blocks had theidentical tendon engaging surface which was sawtooth. Substantiallyidentical segments of allograft tendon were cut and sized prior tosandwiching between a design block (01-05) and an opposing bone block.For each of designs 01-05, bone block-tendon assemblies were made intriplicate and then tested. Testing was accomplished on an Instron Model5800 force testing machine, Canton, Mass. by measuring the load tofailure (N) for each bone block-tendon assembly. Failure occurred whenthe tendon was pulled free from the bone block assembly. The mean loadto failure from the triplicate measurements was then calculated andreported in Table 2.

Referring to Table 2, it is apparent that decreasing the surface area ofthe intermediate bone block of this invention (designs 01-05)surprisingly increases the mean load to failure of the tendon in thebone block-tendon assembly. For example, in going from design 1 (double“I” layout) to design 02 (inverted “U” layout), which involved adding achannel that runs across the direction of pull under the same controlledconditions, there resulted an increase in mean load to failure of 14 N.In going from design 02 (inverted “U” layout) to design 03 (inverted big“U” layout), which involved increasing the width of the channel at thecurved base of the “U,” there resulted an increase in mean load tofailure of 8 N under the same controlled conditions. In going fromdesign 02 (inverted “U” layout) to design 04 (“A” shaped layout), whichinvolved adding a cross channel at about the middle of the block toconvert the inverted “U” to an “A” shaped layout, surprisingly increasedthe mean load to failure by 40 N under the same controlled conditions.Adding a second cross channel to design 04 to produce design 05 (havinga double stacked “A” layout (or a triple stacked “U” layout, dependingupon your perspective)), further increases the mean load to failure ofthe tendon in the bone block-tendon assembly by 5 N to 565 N. In eachcase, the decrease in surface area corresponded to a proportionallylarger increase in percent volume removed.

The various embodiments of the of the intermediate bone blocks, the boneblock assemblies and the assembled BTBs of the present invention can bebetter understood by reference to the Figures.

FIG. 1 is a view of a first comparative bone block-tendon assembly 10comprising two bone blocks (1 and 2) that sandwich a tendon 3, each boneblock having a completely smooth (flat) tendon engaging surface. FIG. 1is an exploded view of the first comparative bone block assembly 10.This first comparative bone block-tendon assembly 10 is tested foraverage load to failure (Newtons) in Table 1 relative to boneblock-tendon assemblies of FIGS. 2-5, each having at least one differenttendon engaging surface. When this bone block-tendon assembly 10 wasmade and comparatively tested for load strength relative to othersubstantially identical bone tendon assemblies that differed solely intheir tendon engaging surfaces, this bone block-tendon assembly faredthe worst and only had a mean load to failure of 260 N. See Table 1.

FIGS. 2A-2B provide views of a second comparative bone block-tendonassembly 20 comprising two bone blocks (1 and 4) that sandwich a tendon3, the first bone block 1 having a smooth tendon engaging surface whilethe second bone block 4 has a saw tooth pattern or ridges on its tendonengaging surface. FIG. 2A is an exploded view of the second comparativebone block assembly. FIG. 2B is a detailed view of the tendon and boneblocks from FIG. 2A. When this bone block-tendon assembly 20 was madeand comparatively tested for average load to failure relative to othersubstantially identical bone tendon assemblies that differed solely intheir tendon engaging surfaces, this bone block-tendon assembly faredbetter that the flat:flat tendon engaging surface. In particular, thisbone block-tendon assembly 20 had an average load to failure of 344N.See Table 1. Thus, substituting a bone block 4 having a saw toothpattern of ridges as a textured surface for bone block 2 having a flat(smooth) surface increased the load required to induce failure of theresulting bone block tendon assembly 20 by 84 N (or by 32%) under thesestandardized conditions.

FIG. 3 is a drawing of a third comparative bone block-tendon assemblycomprising two bone blocks that sandwich a tendon, each bone blockhaving a textured (saw-tooth pattern) pattern of ridges on its tendonengaging surface. This third comparative bone block-tendon assembly wasmade and tested for average load to failure (Newtons) in Table 1relative to bone block-tendon assemblies of FIGS. 1, 2A-2B, 4A-4B, and5A-5B, each having at least one different tendon engaging surface. Sincesubstituting one of the flat tendon engaging surfaces of FIG. 1 with atextured (saw tooth pattern of ridges) tendon engaging surface as inFIG. 2 produced a 32% improvement in load until failure, one would havethought that substituting the remaining bone block with the flat tissueengaging surface of FIG. 2A with another bone block with a textured (sawtooth pattern of ridges) would have resulted in a bone block-tendonassembly with an increased the load at failure relative to the assemblyof FIG. 2A. However, the resulting bone block-tendon assembly of FIG. 3Ahad an average load to failure of 343 N, and thus produced noimprovement over the bone block-tendon assembly of FIG. 2A under thesestandardized conditions.

FIGS. 4A-4D are views of a fourth comparative bone block-tendon assembly40 comprising two bone blocks that sandwich a tendon 3, the first boneblock 4 having a textured pattern (saw-tooth pattern of ridges) on itstendon engaging surface (as for FIG. 3) while the second bone block 5 isan intermediate bone block of the present invention having an a smoothtendon engaging (compression) surface that is interrupted by twochannels with rectangular cross-sections 6 running across the directionof pull of the tendon 3. FIG. 4A is an exploded view of the fourthcomparative bone block assembly. FIG. 4B is a side view of the assembledfourth comparative bone block assembly. FIG. 4C is an end view FIG. 4Dis a detailed view of the tendon and bone blocks from FIG. 4A showingthe lengthwise channels having a rectangular cross-section in theintermediate bone block of the present invention. This fourthcomparative bone block-tendon assembly was made and tested for averagefailure load (Newtons) in Table 1 relative to bone block-tendonassemblies of FIGS. 1, 2A-2B, 3A-3B and 5A-5D, each having at least onedifferent tendon engaging surface. Surprisingly, the resulting boneblock-tendon assembly 40 of FIGS. 4A-4D had an average load to failureof 426 N, and thus produced an 83 N (24%) improvement over the boneblock-tendon assembly of FIG. 3A and a 166 N (64%) improvement over thebone block tendon assembly 10 of FIG. 1 under these standardizedconditions.

FIGS. 5A-5D are views of a fifth comparative bone block-tendon assembly50 comprising two bone blocks (4 and 7) that sandwich a tendon 3, thefirst bone block 4 having a textured pattern (saw-tooth pattern ofridges) on its tendon engaging surface while the second bone block 7 isa preferred intermediate bone block of the present invention having an asmooth tendon engaging (compression) surface that is interrupted by twochannels 8 with omega cross-sections running in the direction of pull ofthe tendon 3. FIG. 5A is an exploded view of the fifth comparative boneblock assembly. FIG. 5B is a side view of the assembled fifthcomparative bone block assembly. FIG. 5C is an end view FIG. 5D is adetailed view of the tendon and bone blocks from FIG. 5A showing thelengthwise channels having a rectangular cross-section in theintermediate bone block of the present invention. This fifth comparativebone block-tendon assembly 50 was made and tested for average load tofailure (Newtons) in Table 1 relative to bone block-tendon assemblies ofFIGS. 1, 2A-2B, 3A-3B, and 4A-4D, each having at least one differenttendon engaging surface. Surprisingly, just changing the shape of thetwo channels in the bone block-tendon assembly of FIGS. 4A-4D fromhaving a rectangular to an omega cross section to produce the bone blocktissue assembly of FIGS. 5A-5D, resulted in a bone-block tendon assemblythat would not fail until an average load of 516 N. This change inchannel cross sectional shape resulted in an additional 90 N of load tofailure or an increase in load to failure of 21% relative the bone blocktendon assembly of FIGS. 4A-4D. Viewed from another perspective, merelyswapping the intermediate bone block of the present invention (with theomega cross section) for one of the textured bone blocks of FIGS. 3A-3Bresulted in a gain in load to failure of 173 N (a 50% increase) over theassembly of FIGS. 3A-3B under these standardized test conditions.

Thus, the intermediate bone blocks of the present invention, which arecharacterized by the interruption of the soft tissue (e.g., tendon)engaging surface of a bone block with 1-10 surface cavities,particularly channels, and particularly the channels with the undercutor omega cross section, provide enhanced gripping of a soft tissue(particularly a tendon) without tearing or cutting, in a boneblock-tendon assembly, such as used in Applicants' assembled BTB.

FIGS. 6A-6D show various views of the textured bone block 60 used in theassemblies of FIGS. 2-5, wherein the texture was a saw-tooth pattern onthe tissue (e.g., tendon) engaging surface. FIG. 6A is a perspectiveview of the textured bone block 60, having opposing end walls 64 and 65,side wall 63, and showing rows of ridges 62 in a saw tooth patternangled away from the direction of pull of the tendon (arrow). FIG. 6B isa top view of the textured bone block looking directly down at thesaw-tooth pattern of ridges on the (soft) tissue engaging surface 61.FIG. 6C is a side view of the textured bone block showing the pattern ofridges 62 which look like angled teeth from this perspective. FIG. 6D isa blow-up of the details of the angled ridges shown in 6D, having aheight A and an attack angle B.

FIGS. 7A-7D show various views of an alternative textured bone block 70,wherein the texture is a pattern of ridges and valleys on the tendonengaging surface. FIG. 7A is a perspective view of the textured boneblock 70, having opposing end walls 74 and 75, side wall 73 and atextured soft tissue engaging surface 71. FIG. 7B is a top view of thetextured bone block 70 looking directly down at the textured pattern onsoft tissue engaging surface 71. FIG. 7C is a side view of the texturedbone block showing the pattern of mounds 76 and valleys 77 on the softtissue (e.g., tendon) engaging surface 71. FIG. 7D is an end view of thetextured bone block of FIG. 7A showing a different perspective of themounds and valleys. As shown, the pattern of mounds and valleys issymmetrical. However, it is also within the scope of the presentinvention that the mounds be angled to preferentially engage the softtissue in one direction as shown in FIG. 6A.

FIGS. 8A-8D show a series of views of one embodiment of an intermediatebone block of the present invention having channels 87 with a squarecross section running substantially perpendicular to the length of thebone block 80 and the intended direction of pull (arrow) of a segment ofsoft tissue (e.g., tendon). Even if one direction if pull is indicated,it is within the scope of the present invention that the intermediatebone blocks be used in a bone block assembly in either lengthwiseorientation (shown as a double headed arrow). FIG. 8A is a perspectiveview of the intermediate bone block 80, having opposing end walls 84 and85, side wall 83, and soft tissue engaging surface 81. The soft tissueengaging surface 81 is broken up by a series of channels 87 having asquare cross section, leaving a plurality of isolated tissue compressionsurfaces 86. FIG. 8B is a top view of the intermediate bone blocklooking directly down at the layout (pattern) of channels 87 in tissueengaging surface 81. FIG. 8C is a side view of the intermediate boneblock showing the pattern of cavities (e.g., channels 87) with a squarecross section and a plurality of tissue compression surfaces 86bordering the channels 87. When the width A and the depth B of thechannels are equal, the cross section of the channels is a square.However, it is also within the scope of the present invention that A andB are not equal, such that the cross section of the channel 87 is arectangle. FIG. 8D is a view of the intermediate bone block 80 of FIG.8A viewed from end 84.

The size range in the intermediate bone blocks of the present inventionare based upon the intended use of the bone block and in some instancesthe size of the patient. Typical sizes of the intermediate bone blockrange in length from 10 mm to 50 mm; in width from 2 mm to 15 mm; and inheight or diameter from 2 mm to 15 mm. Preferably, the length rangesfrom from 15 mm to 35 mm; more preferably from 20 mm to 25 mm.Preferably, the width ranges from from 6 mm to 13 mm; more preferablyfrom 9 mm to 12 mm. Preferably, the height or diameter ranges from 6 mmto 13 mm; more preferably from 9 mm to 12 mm.

FIGS. 9A-9D show views of another embodiment of an intermediate boneblock of the present invention having a plurality of channels 97 runningsubstantially perpendicular to the length of the bone block 90 and theintended direction of pull (arrow) of a segment of soft tissue (e.g.,tendon). The plurality of channels 97 are similar to the channels 87 inFIGS. 8A-8D except that the bottom edges of the channels 97 have aradius (R) edge. FIG. 9A is a perspective view of the intermediate boneblock 90, having opposing end walls 94 and 95, side wall 93, and softtissue engaging surface 91. The soft tissue engaging surface 91 isbroken up by a series of channels 97 having a rounded square crosssection, leaving a plurality of isolated tissue compression surfaces 96.FIG. 9B is a top view of the intermediate bone block 90 looking directlyon soft tissue engaging surface 91, which is characterized by aplurality of channels 97 interrupting the surface and leaving aplurality of isolated soft tissue compression surfaces 96. FIG. 9C is aside view of the intermediate bone block showing the pattern of cavities(e.g., channels 97) and tissue compression surfaces 96. The crosssection of the channels 97 is shown as square with rounded edges (i.e.,a rounded square). In this embodiment as shown, the depth B of thechannel 97 equals its width A. However, it is also within the scope ofthe present invention that A and B are not equal, such that the crosssection of the channel 97 is a rectangle. FIG. 9D is a view of theintermediate bone block 90 of FIG. 9A viewed from end 94.

FIGS. 10A-10D show a series of views of another embodiment of anintermediate bone block of the present invention having a plurality ofchannels 107 running substantially perpendicular to the length of thebone block 100 and the intended direction of pull (arrow) of a segmentof soft tissue (e.g., tendon). The plurality of channels 107 have atriangular cross section. FIG. 10A is a perspective view of theintermediate bone block 100, having opposing end walls 104 and 105, sidewall 103, and soft tissue engaging surface 101. The soft tissue engagingsurface 101 is broken up by a series of channels 107 having a triangular(“V” shaped) cross section, leaving a plurality of isolated tissuecompression surfaces 106. FIG. 10B is a top view of the intermediatebone block 100 looking directly on soft tissue engaging surface 101,which is characterized by a plurality of channels 107 interrupting thesurface and leaving a plurality of isolated soft tissue compressionsurfaces 106. FIG. 10C is a side view of the intermediate bone blockshowing the pattern of cavities (e.g., channels 107) and tissuecompression surfaces 106. The cross section of the channels 107 is shownas triangular. In this embodiment as shown, the channel has a depth Band an angle A at its tip. While the triangular channel is shown asequilateral, it is also within the scope of the present invention thatthe side walls of the triangle not be equal. FIG. 10D is a view of theintermediate bone block 100 of FIG. 10A viewed from end 104.

FIGS. 11A-11D show a series of views of one preferred embodiment of anintermediate bone block of the present invention as used in the testblock of FIG. 5 and Table 1. FIG. 11A is a perspective view of oneembodiment on an intermediate bone block 110 having opposing end walls114 and 115, side wall 113, and two channels 117 with an (inverted)omega-shaped cross section running the length of the bone block andsubstantially in the intended direction of pull (arrow) of a segment ofsoft tissue (e.g., tendon). The two channels 116 are surrounded by softtissue compression surfaces 116. FIG. 11B is a top view of theintermediate bone block looking directly down on soft tissue engagingsurface 111, having two channels 117 surrounded by soft tissuecompression surfaces 116. FIG. 11C is a side view of the intermediatebone block 110, showing that the channels have a substantially uniformdepth. However, it is also within the scope of the present inventionthat the channels 117 have a slope (as also shown elsewhere) betweenopposing ends 114 and 115, or have incremental changes in depth. FIG.11D is an end view of the intermediate bone block 110 viewed from end114, showing the cross sectional (omega) shape of the channels 117. Ifthe block of FIG. 11D is rotated 180° in the plane of the paper, theomega (“Ω”) shape of channel 117 becomes more apparent.

FIGS. 12A-12D show a series of views of one preferred embodiment of anintermediate bone block of the present invention. FIG. 12A is aperspective view of one embodiment on an intermediate bone block 120having opposing end walls 124 and 125, side wall 123, and two channels127 with an omega-shaped cross section running the length of the boneblock and substantially in the intended direction of pull (arrow) of asegment of soft tissue (e.g., tendon). The two channels 126 aresurrounded by soft tissue compression surfaces 126. End 124, which isthe end from which the soft tissue (e.g., tendon) would extend and bepulled has a radius curve 128 to minimize any sharp edge that could cutinto the tendon or fray its edges. This results in an internal leadingedge configuration that reduces tissue stresses during assembly and use.FIG. 12B is a top view of the intermediate bone block looking directlydown on soft tissue engaging surface 121, having two channels 127surrounded by soft tissue compression surfaces 126. FIG. 12C is a sideview of the intermediate bone block 120, showing that the channels havea substantially uniform depth. However, it is also within the scope ofthe present invention that the channels 127 have a slope (as also shownelsewhere) between opposing ends 124 and 125, or have incrementalchanges in depth. FIG. 12D is an end view of the intermediate bone block120 viewed from end 124, showing the cross sectional (omega) shape ofthe channels 127. If the block of FIG. 12D is rotated 180° in the planeof the paper, the omega (“Ω”) shape of channel 127 becomes moreapparent.

FIGS. 13A-13D show a series of views of one embodiment of anintermediate bone block of the present invention having channels 137with an omega shaped cross section running substantially perpendicularto the length of the bone block 130 and the intended direction of pull(arrow) of a segment of soft tissue (e.g., tendon). FIG. 13A is aperspective view of the intermediate bone block 130, having opposing endwalls 134 and 135, side wall 133, and soft tissue engaging surface 131.The soft tissue engaging surface 131 is broken up by a series ofchannels 137 having an omega shaped square cross section, leaving aplurality of isolated tissue compression surfaces 136. FIG. 13B is a topview of the intermediate bone block looking directly down at the layout(pattern) of channels 137 cut into tissue engaging surface 131, leavingfour soft tissue compression surfaces separated by the channels. FIG.13C is a side view of the intermediate bone block showing the omegacross-sectional shape of the channels. More particularly, when the blockof FIG. 13C is rotated 180° in the plane of the paper, the omega (“Ω”)shape of channel 137 becomes more apparent. FIG. 13D is a view of theintermediate bone block 130 of FIG. 13A viewed from end 134.

FIGS. 14A-14D show various views of yet another embodiment of anintermediate bone block of the present invention having a plurality ofchannels with different sized omega-shaped cross sections runningsubstantially perpendicular to the length of the bone block 140 and theintended direction of pull (arrow) of a segment of soft tissue (e.g.,tendon). As reflected in the double sided arrow, this bone block whichhas an asymmetrical layout of channels may have the segment of softtissue pull in either direction. FIG. 14A is a perspective view of thisembodiment on an intermediate bone block, having opposing ends 144 and145, side 143, tissue engaging surface 141 that is broken up by threedifferent sized channels (147A, 147B and 147C) with omega shaped crosssections, leaving four soft tissue compression surfaces. FIG. 14B is atop view of the intermediate bone block looking directly down at thepattern of channels. FIG. 14C is a side view of the intermediate boneblock, showing the pattern of cavities (e.g., channels) and tissuecompression surfaces. If the block of FIG. 14C is rotated 180° in theplane of the paper, the omega shape of each of different sized channels147A, 147B and 147C become apparent. FIG. 14D is an end view of theintermediate bone block of FIG. 14A as viewed from end 144.

FIGS. 15A-15D show various views of yet another embodiment of anintermediate bone block of the present invention. FIG. 15A is aperspective view of one embodiment on an intermediate bone block 150,having opposing ends 154 and 155, sidewall 153 running the length of thebone block 150, soft tissue engaging surface 151 that is broken up by alayout of channels 157B with an (inverted) omega-shaped cross sectionrunning substantially perpendicular to the length of the bone block 150across the intended direction of pull (arrow) of a segment of softtissue (e.g., tendon) and more channels 157A with an (inverted)omega-shaped cross section running substantially in the intendeddirection of pull (arrow) of a segment of soft tissue (e.g., tendon).The layout of channels cut into tissue engaging surface 151 leave behinda plurality of soft tissue (e.g., tendon) compression surfaces 156. FIG.15B is a top view of the intermediate bone block looking directly downat tissue engaging surface 151 having criss-crossing channels 157A and157B producing a waffle pattern of plateaus of tissue compressionsurfaces 156. FIG. 15C is a side view of the intermediate bone blockshowing the pattern of cavities (e.g., channels) 157B with the omegashaped cross section. FIG. 15D is an end view of the intermediate boneblock of FIG. 15A also showing a lengthwise view of channels 157A havingthe omega shaped cross-section. If the views of FIGS. 15C and 15D arerotated 180° in the plane of the paper, the omega cross-sectional shapeof channels 157B and 157A, respectively becomes more apparent.

FIGS. 16A-16D show various views of yet another embodiment of anintermediate bone block of the present invention having a plurality ofchannels with omega-shaped cross sections running generally widthwiseand across the intended direction of pull (arrow) of a segment of softtissue (e.g., tendon). FIG. 16A is a perspective view of intermediatebone block 160, having opposing ends 164 and 165, sidewall 163 runningthe length of the bone block 160, soft tissue engaging surface 161 thatis broken up by a “V” shaped layout of channels 167 with an (inverted)omega-shaped cross section running substantially across the intendeddirection of pull (arrow) of a segment of soft tissue (e.g., tendon).The layout of channels 167 cut into tissue engaging surface 161 leavebehind a plurality of soft tissue (e.g., tendon) compression surfaces166. The asymmetry of the layout of the channels does not limit the boneblock to be limited to one particular direction of use. As shown in thedouble headed arrow, the bone block 160 can be used in either lengthwisedirection relative to the direction of pull of the soft tissue. FIG. 16Bis a top view of the intermediate bone block looking directly down attissue engaging surface 161 having a “V” shaped layout of four channels167 cut therein, leaving a plurality of tissue compression surfaces 166.FIG. 16C is a side view of the intermediate bone block showing the(inverted) omega cross sectional shape of the channels 167. If the blockof FIG. 16C is rotated 180° in the plane of the paper, the omega (“Ω”)shape of the channels 167 becomes more apparent. FIG. 16D is an end viewof the intermediate bone block 160 of FIG. 16A viewed from end 164.

FIGS. 17A-17D show a series of views of a more preferred embodiment ofan intermediate bone block of the present invention. FIG. 17A is aperspective view of intermediate bone block 170, having opposing ends174 and 175, sidewall 173 running the length of the bone block 170, softtissue engaging surface 171 that is broken up by a stacked/overlappingdouble “A” (or stacked or overlapping triple “U”) pattern of channels177 (as tested in Table 2). In this embodiment, the layout of thechannels has a first component that runs lengthwise parallel wall 173and in the intended direction of pull (arrow) of a segment of softtissue (e.g., tendon), and a second component that runs widthwise and/oracross the intended direction of pull of the tendon. The layout ofchannels 177 that are cut into tissue engaging surface 171 leave behinda plurality of soft tissue (e.g., tendon) compression surfaces 177.While the embodiment of FIG. 17A shows the triple “U” pattern, it isalso within the scope of the present invention that the channel layoutbe a single “U” pattern (as in designs 2 and 3 of Table 2) or a double“U” pattern. FIG. 17B is a top view of the intermediate bone blocklooking directly down at the triple “U” shaped layout of the channels.FIG. 17C is a side view of the intermediate bone block showing thepattern of cavities (e.g., channels) and tissue compression surfaces. Ifthe block of FIG. 17C is rotated 180° in the plane of the paper, theomega (“Ω”) shape of the channels 177 becomes apparent. FIG. 17D is anend view of the intermediate bone block of FIG. 17A.

FIGS. 18A-18D show a series of views of another embodiment of anintermediate bone block of the present invention. This embodiment isessentially the intermediate bone block of FIGS. 11A-11B that ismodified to have as its tendon engaging surface the textured surface ofFIGS. 6A-6C. Other textured surfaces can be utilized in the same manneras the tendon engaging surface, e.g., that shown in FIGS. 7A-7D. FIG.18A is a perspective view of intermediate bone block 180, havingopposing ends 184 and 185, sidewall 183 running the length of the boneblock 180, soft tissue engaging surface 181 having rows of ridges 189angled to engage the soft issue in the direction of pull of the tendon,the soft tissue engaging surface being broken up by two channels 187 cuttherein, the channels running the length of the bone block 180 andhaving an (inverted) omega-shaped cross section. FIG. 18B is a top viewof the intermediate bone block 180 looking directly down at tissueengaging surface 181 and the two substantially parallel channels 187 cuttherein, leaving three textured soft tissue compression surfaces 186.FIG. 18C is a side view of the intermediate bone block showing the sawtooth pattern of angled ridges 189 appearing as angled teeth in thisperspective. FIG. 18D is an end view of the intermediate bone block ofFIG. 18A viewed from end 184, showing the omega shaped cross section ofchannels 187. If the block of FIG. 18D is rotated 180° in the plane ofthe paper, the omega (“Ω”) shape of each of channels 187 becomes moreapparent.

FIGS. 19A-19D show a series of views of the external profile of oneembodiment of an intermediate bone block of the present invention. FIGS.19A-19D are essentially views of the flip side of the intermediate boneblock of FIG. 11A-11D, respectively, wherein all outside edges wererounded to have a radius. FIG. 19A is a perspective view of intermediatebone block 190, having opposing ends 194 and 195 each with a radius edge199 of radius R1, sidewall 193 extending the length of the bone block190 and having radius edge 198 of radius R2. The radius R1 typicallyranges from 0.5 mm to 5 mm. The radius R2 typically ranges from 0.5 mmto 5 mm. FIG. 19B is a top view of the intermediate bone block 190 ofFIG. 19A, showing an exterior surface 196 opposite the tissue engagingsurface 191 (not shown) and radius edges 198 and 199. FIG. 19C is a sideview of the bone block 190 of FIG. 19A showing the outside cornershaving a rounded edge of radius R1, and showing as a broken line theinternal omega shaped channel running the length of the bone block. FIG.19D is an end view of the intermediate bone block of FIG. 19A viewedfrom its end 194 and looking down the length of the two channels 197having the omega (“Ω”) shaped cross section in upright form in thisperspective. Alternative embodiments of shapes for the outer surface ofthe intermediate bone block or bone block assembly include but are notlimited to polygonal, cylindrical, threaded, bulleted, chamfered,angled, ridged, capsule shaped, tapered or a combination thereof.

FIGS. 20A-20D show a series of views of one embodiment for the exteriorshape of an intermediate bone block of the present invention. Thisembodiment essentially superimposes a capsule shape on the intermediatebone block of FIGS. 11A-11D. FIG. 20A is a perspective view of capsuleshaped intermediate bone block 200, having soft tissue (e.g. tendon)engaging surface 201 with two channels 207 cut therein and running thelength of the capsule, the channels 207 having in this view an(inverted) omega-shaped cross section. Soft tissue engaging surface 201also has three soft tissue compression surfaces 206 that are interruptedby two holes 202, sized and placed for receiving a pin (not shown) thatwould engage and penetrate any soft tissue thereon and any opposing boneblock face thereon. The length of any of the capsule shaped intermediatebone blocks of the present invention typically range from 10 mm to 50mm, more typically from 15 mm to 35 mm, preferably from 20 mm to 25 mm.FIG. 20B is a top view of the soft tissue engaging face 201 of theintermediate bone block 200 looking directly down at the pattern ofchannels 207 and pin holes 202. The undercut nature of the omegachannels is seen as the broken lines running parallel channels 207. Thisview also shows the capsular shape of the bone block which facilitatesits introduction into a bone tunnel in a patient to be treated. Each ofthe ends of the bone block have a first radius R1. The radius R1 rangesfrom 3 mm to 10 mm. Alternatively, the radius R1 may be defined suchthat it creates a full round across the entire end of the bone block.Each of the ends of the bone block have a second radius R2. The radiusR2 ranges from 3 mm to 10 mm. Alternatively, the radius R2 may bedefined such that it creates a full round across the entire end of thebone block assembly when assembled with another bone block havingsimilar external geometry. The body of the cylinder has a radius R3.Typical dimensions of a circular surgical bone tunnel have a diameter ofbetween about 7 mm and 12 mm. Hence, a typical diameter (2×R3) of thesemi capsular bone block 200 is from about 7 mm to about 12 mm,respectively or slightly smaller. Different combinations of radiusvalues for R1, R2, and R3 will result in tangent, truncated, or sharpcorner edge transitions between the end of the bone block and the bodyof the bone block., e.g., 7 mm diameter bone block with a 10 mm R1 willproduce a sharp edge or corner between the body and the end as seen inFIG. 20B, while a 10 mm diameter bone block with a 5 mm R1 will producea tangent edge between the end of the bone block and the body of thebone block. FIG. 20C is a side view of the intermediate bone block 200showing another view of its semi-capsular shape. In this perspective,which is rotated 90° along the long axis of the capsule in FIG. 20B, theradius at each end remains R1 as in FIG. 20B. FIG. 20D is an end view ofthe intermediate bone block of FIG. 20A. If the block of FIG. 20D isrotated 180° in the plane of the paper, the omega shape (“Ω”) of channel207 becomes more apparent.

FIGS. 21A-21D show various views of the exterior surface of asemi-capsule shaped embodiment of a bone block. The semi-capsular boneblock of FIGS. 21A-21D can serve as the opposing bone block to the boneblock of FIGS. 20A-20D. FIG. 21A is a perspective view of semi capsularbone block 210 showing holes 212 for receiving a biocompatible pin (notshown) that would hold this bone block to any one of a variety ofappropriately shaped intermediate bone blocks (of the present invention)and to a segment of soft tissue sandwiched therebetween. FIG. 21B is atop view of the outside face of this opposing bone block lookingdirectly down at its capsule shape, having ends with radius R1 and holes212 for receiving an interference pin. The radius R1 typically rangesfrom 3 mm to 10 mm. Alternatively, the radius R1 may be defined suchthat it creates a full round across the entire end of the bone block.Each of the ends of the bone block have a second radius R2. The radiusR2 ranges from 3 mm to 10 mm. Alternatively, the radius R2 may bedefined such that it creates a full round across the entire end of thebone block assembly when assembled with another bone block havingsimilar external geometry. The body of the cylinder has a radius R3.Typical dimensions of a circular surgical bone tunnel have a diameter ofbetween about 7 mm and 12 mm. Hence, a typical diameter (2×R3) of thesemi capsular bone block 210 is from about 7 mm to about 12 mm,respectively or slightly smaller. Different combinations of radiusvalues for R1, R2, and R3 will result in tangent, truncated, or sharpcorner edge transitions between the end of the bone block and the bodyof the bone block., e.g., 7 mm diameter bone block with a 10 mm R1 willproduce a sharp edge or corner between the body and the end as seen inFIG. 21B, while a 10 mm diameter bone block with a 5 mm R1 will producea tangent edge between the end of the bone block and the body of thebone block. FIG. 21C is a side view of the opposing bone block 210showing its semi-capsular shape. In this perspective, which is rotated90° along the long axis of the capsule in FIG. 21B, the radius at eachend remains R1 as in FIG. 21B. FIG. 21D is an end view of the opposingbone block of FIG. 21A. When the bone block of FIG. 21A has channels(not shown) on its tissue engaging surface 211, it becomes anintermediate bone block of the present invention. In the presentembodiment, the opposing bone block 210 is shown with a flat tissueengaging surface 211. However, it is also within the scope of thepresent invention that the opposing bone block (to any of Applicants'intermediate bone blocks) also have a textured surface, two of which areexemplified in FIGS. 6A-6C and 7A-7D.

FIGS. 22A-22D show a series of views of an embodiment of the exteriorprofile of an intermediate bone block of the present invention. FIG. 22Ais a perspective view of the exterior surface of intermediate bone block220, which is analogous to the intermediate bone block of FIGS. 20A-20D,except that intermediate bone block 220 has a longitudinal groove 229running its length. Groove 229 has radius R, which is suitable formaximizing radial contact with an interference screw (not shown). Groove229 also has two holes 222 positioned thereon and suitably sized forreceiving an interference pin (not shown) which would hold intermediatebone block 220 to a suitably sized opposing bone block (e.g., 200 or210) and a segment of soft tissue sandwiched therebetween. Intermediatebone block 220 also has a pair of channels 22 with an omega shaped crosssection running the length of its tissue engaging surface 221. FIG. 22Bis a top view of intermediate bone block 220 looking directly down atits capsular shape from this perspective, having opposing ends with aradius R1, centrally positioned groove 229, and the two symmetricallyplaced pin holes 222 in the groove 229. In an alternate embodiment, thegroove is positioned off center. The radius R1 typically ranges from 3mm to 10 mm. Alternatively, the radius R1 may be defined such that itcreates a full round across the entire end of the bone block. Each ofthe ends of the bone block have a second radius R2. The radius R2 rangesfrom 3 mm to 10 mm. Alternatively, the radius R2 may be defined suchthat it creates a full round across the entire end of the bone blockassembly when assembled with another bone block having similar externalgeometry. The body of the cylinder has a radius R3. Typical dimensionsof a circular surgical bone tunnel have a diameter of between about 7 mmand 12 mm. Hence, a typical diameter (2×R3) of the semi capsular boneblock 220 is from about 7 mm to about 12 mm, respectively or slightlysmaller. Different combinations of radius values for R1, R2, and R3 willresult in tangent, truncated, or sharp corner edge transitions betweenthe end of the bone block and the body of the bone block., e.g., 7 mmdiameter bone block with a 10 mm R1 will produce a sharp edge or cornerbetween the body and the end as seen in FIG. 22B, while a 10 mm diameterbone block with a 5 mm R1 will produce a tangent edge between the end ofthe bone block and the body of the bone block. FIG. 22C is a side viewof the intermediate bone block showing its semi-capsular shape and thepositions of the holes 222 running through to tissue engaging surface221. FIG. 22D is an end view of the intermediate bone block of FIG. 22A,showing the generally hemispherical shape of radius R3 interrupted bygroove 229 having a radius R. The radius R typically ranges from 1 mm to10 mm. Typically, an intermediate bone block has 1 such groove for aninterference screw, alternatively an intermediate bone block can have 2to 6 such grooves, resulting in final bone block assemblies with groovesto accommodate from 1 to 12 interference screws, preferably 1 to 6interference screws, more preferably 2 to 4 interference screws. Groovesfor interference screws have threads, tapped threads or no threads. Inan alternate embodiment, grooves for interference screws arespecifically not included (e.g., when other fixation methods are used).In another alternate embodiment, a same or similar groove is included inthe design to accommodate soft tissue that is external to the bone blockassembly. Looking longitudinally down the capsular shape, there is apair of channels 22 having an omega shaped cross section. In practice,this intermediate bone block may serve as the opposing bone block forthe bone blocks of FIGS. 20A-20D or FIGS. 21A-21D.

FIGS. 23A-23D show views of an alternate embodiment for the exteriorsurface of an intermediate bone block 230 of the present invention.Intermediate bone block 230 is semi-capsule shaped bone block that canbe combined with the opposing bone block of FIGS. 20A-20D, 21A-21D,22A-22D or itself 23A-23D. FIG. 23A is a perspective view ofsemi-capsule shaped intermediate bone block 230, having rounded opposingends of radius R1, holes 232 for receiving a biocompatible pin (notshown) that would hold this bone block to any one of a variety ofappropriately shaped intermediate bone blocks and to a segment of softtissue sandwiched therebetween. Also shown on the exterior surface ofthis embodiment are ridges 239 suitable for gripping a bone tunnel andreducing slippage in the direction of pull (arrow) of the tendon.Alternative embodiments of shapes for the outer surface of theintermediate bone block or bone block assembly include but are notlimited to polygonal, cylindrical, threaded, bulleted, chamfered,angled, ridged, capsule shaped, tapered or a combination thereof. FIG.23B is a top view of the outside face of this intermediate bone block230 looking directly down at its capsule shape (from this perspective)and the position of the pin holes 232. In this figure, the hemisphericalends have radius R1, and the ridges project at an angle “C”. The angle Cranges from 1° to 60°. The radius R1 typically ranges from 3 mm to 10mm. Alternatively, the radius R1 may be defined such that it creates afull round across the entire end of the bone block. Each of the ends ofthe bone block have a second radius R2. The radius R2 ranges from 3 mmto 10 mm. Alternatively, the radius R2 may be defined such that itcreates a full round across the entire end of the bone block assemblywhen assembled with another bone block having similar external geometry.The body of the cylinder has a radius R3. Typical dimensions of acircular surgical bone tunnel have a diameter of between about 7 mm and12 mm. Hence, a typical diameter (2×R3) of the semi capsular bone block230 is from about 7 mm to about 12 mm, respectively or slightly smaller.Different combinations of radius values for R1, R2, and R3 will resultin tangent, truncated, or sharp corner edge transitions between the endof the bone block and the body of the bone block., e.g., 7 mm diameterbone block with a 10 mm R1 will produce a sharp edge or corner betweenthe body and the end as seen in FIG. 23B, while a 10 mm diameter boneblock with a 5 mm R1 will produce a tangent edge between the end of thebone block and the body of the bone block. FIG. 23C is a side view ofthe intermediate bone block 230 showing its semi-capsular shape andchannel 237 running its length. FIG. 23D is an end view of theintermediate bone block 230, showing the generally hemispherical shapeof radius R1. The radius R1 ranges from 3 mm to 10 mm. Lookinglongitudinally down the capsular shape, there is a pair of channels 22having an omega shaped cross section. In practice, this intermediatebone block may be combined with the bone block of FIG. 20A, FIG. 21A,FIG. 22A or preferably FIG. 23A.

FIGS. 24A-D are views of one embodiment of a BTB of the presentinvention, defined as a length of soft tissue (e.g., typically tendon orligament) having opposing ends and a bone block-tendon assembly at eachof the opposing ends. FIG. 24A is a perspective view of an assembled BTB240 of the present invention. In this perspective view, the BTB 240 iscomposed of a predetermined length of soft tissue 243 having opposingends with bone blocks 244 and 245 sandwiching the soft tissue 243 at afirst opposing end and bone blocks 241 and 246 sandwiching the softtissue 243 at its second opposing end. The bone blocks 241, 244, 245 and246 may be the same or different. At least one of the bone blocks ateach opposing end is an intermediate bone block of the presentinvention. Preferably, one of the bone blocks at each end has 1-10channels on the soft tissue engaging surface, wherein the channel(s) hasan omega shaped cross section. The soft tissue 243 can be any of thesoft tissues described herein. Pins 242 are inserted in holes in theopposing bone blocks and provide an interference fit, holding the boneblocks in juxtaposition and sandwiching the soft tissue therebetween toform a unitary device. The pins can be any of the pins described herein.Preferably, they are cortical bone pins. FIG. 24B is a top view of theassembled BTB 240, wherein one embodiment for positioning two bone pinsis shown. It is within the scope of the present invention to have up to30 pins. Typically, 1-5 pins are used per bone block assembly. Moretypically, 2-3 pins are used per bone block assembly. FIG. 24C is a sideview of the assembled BTB clearly showing the soft tissue 243 sandwichedbetween opposing bone blocks at each end. FIG. 24D is an end view of theassembled BTB 240 clearly showing the soft tissue 243 sandwiched betweenopposing bone blocks 244 and 245 with pin 242 shown as internallytransversing opposing bone blocks 244 and 245, and soft tissue 243sandwiched therebetween.

FIGS. 25A-25D are views of another embodiment of a BTB of the presentinvention. FIG. 25A is an exploded perspective view of a preferredembodiment of an assembled BTB 250 of the present invention. In thisexploded perspective view, the BTB 250 is composed of two assembled boneblock assemblies, one on each of the opposing ends of a segment of softtissue 253 of predetermined length. Typical lengths for the soft tissuedepends upon the application and the size of the patient. In the case ofa BTB intended for anterior cruciate ligament repair in a human patient,the length of the soft tissue between the bone blocks ranges from about32 mm to about 58 mm, preferably from about 38 mm to about 52 mm, andmore preferably from about 42 mm to about 48 mm. In FIG. 25A, each boneblock-tendon assembly has at least one intermediate bone block 251 ofthe present invention as a component thereof. Each of intermediate boneblocks 251 are shown as having soft tissue engaging face 251A with astacked/overlapping triple “U” pattern of channels 257 thereon, eachchannel having the omega-shaped cross section. Intermediate bone blocks251 also have holes 252 for receiving interference pins 257. Bone blocks256 have a groove 258 of a predetermined radius (see the discussion ofFIG. 22) for accommodating the curvature of an interference screw. FIG.25B is a top view of the assembled BTB wherein one embodiment forpositioning three bone pins 257 is shown. Additional holes 259 can beused to accommodate additional pins, or may be used for two pinplacement instead of the currently shown three pin placement, or toaccept suture during surgery for purposes of holding, guiding, orpulling graft into place in the bone tunnel and for tensioning the graftprior to and during fixation. Additional relief or guidance featuressuch as slots, ridges, or small grooves (not shown) allow the suture tobe routed away from the interference screw and thus protected fromdamage or cutting of the suture as the interference screw advances, thusensuring the ability to hold tension on the graft during fixation.Depressions 255 are useful as physical and visual placement aids duringsurgery, as they provide a visual marker for the surgeon to alignfixations devices such as an interference screw, and they also provide aphysical reference point and positive location and contact forinstruments or guide wires to push or guide the graft into place. FIG.25C is a side view of the assembled BTB 250 wherein the bone blocks 256are shown as having a soft tissue engaging face 256A with teeth(actually row of ridges) angled against the direction of pull of thetendon (arrows) and engaging the soft tissue 253. FIG. 25D is an endview of the assembled BTB clearly showing the soft tissue 253 sandwichedbetween opposing semi-capsular bone blocks 251 and 256, having a crosssectional radius R1. In this view, the assembled BTB has the generallycircular diameter of a bone tunnel into which it can be inserted duringa surgical repair of a tendon in a patient in need of such a repair. Inthis view, the groove 258 is visible and would accommodate aninterference screw (not shown) for locking that end of the BTB in itscorresponding bone tunnel. In an alternate embodiment, grooves forinterference screws are specifically not included (e.g., when otherfixation methods are used).

FIGS. 26A-26D are views of another embodiment of a BTB of the presentinvention. FIG. 26A is a perspective view of assembled BTB 260 of thepresent invention. In this perspective view, a length of the soft tissue263 having two opposing ends is wrapped around three sides of bone block265 at its first opposing end and around three sides of bone block 267at its second opposing end, to produce a three layer softtissue:bone:soft tissue sandwich. The segment 263A of the soft tissue263 engages the soft tissue engaging face of bone block 264 to producethe fourth layer of the sandwich. The segment 263B of the soft tissue263 engages the soft tissue engaging face of bone block 266 to producethe fourth layer of the sandwich. In the BTB of 260, at least one of thetwo bone blocks at each end of tendon 263 is an intermediate bone blockof the present invention. Preferably, the soft tissue engaging face ofthe intermediate bone block of the present invention engages soft tissuesegment 263A at the first opposing end and soft tissue segment 263B atits second opposing end. FIG. 26B is a top view of the assembled BTBwherein only the soft tissue 263 is visible. FIG. 26C is cross-sectionalside view CC of the assembled BTB clearly showing the soft tissue 263Aand 263B sandwiched between opposing bone blocks at each end and thepresence of the biocompatible pins 262 holding the opposing bone blocksas an assembled unitary piece. FIG. 26D is a side view of the assembledBTB 260 clearly showing the soft tissue 263A sandwiched between boneblocks 264 and 265 at the first opposing end and soft tissue 263Bsandwiched between bone blocks 267 and 266 at the second opposing end.In an alternate embodiment, a groove (not shown) is included in thedesign to accommodate the soft tissue that is external to the bone blockassembly.

FIGS. 27A-27D are views of another embodiment of a BTB of the presentinvention. FIG. 27A is a perspective view of BTB 270 of the presentinvention, which is essentially BTB 260 of FIG. 26A further comprising athird bone block at each end sandwiching the exterior layer of softtissue above the bone block to produce a five layer assembled sandwich.In particular, FIG. 27A is a perspective view of assembled BTB 270,having a length of the soft tissue 273 having two opposing ends. Thesoft tissue of this BTB or any BTB described herein is selected from anyof the soft tissue described herein. Preferably, the soft tissue is atendon or a ligament or a bundle of 2-10 tendons or 2-20 ligaments, or amixture thereof, any of which are of the same or different lengths,and/or are braided, side-by-side or overlapping. The first opposing endof the soft tissue 273 engages bone block 275 and wraps around threefaces of bone block 275 to produce a soft tissue (273A):bone block(275): soft tissue (273) sandwich. The first soft tissue portion 273A ofthis sandwich is covered with the soft tissue engaging face of boneblock 274 and the second soft tissue portion 273 of the sandwich iscovered with the tissue engaging face of bone block 279, resulting in a5 layer bone:soft tissue:bone:soft tissue:bone sandwich. This 5 memberedsandwich is held together by biocompatible connectors 272, as describedherein, preferably interference pins, more preferably pin of corticalbone that provide an interference fit. Preferred pins are cortical bonepins. The second opposing end of the soft tissue 273 engages bone block277 and wraps around three faces of bone block 277 to produce a softtissue (273B):bone block (277): soft tissue (273) sandwich. The firstsoft tissue portion 273B of this sandwich is covered with the softtissue engaging face of bone block 276 and the second soft tissueportion 273 of the sandwich is covered with the tissue engaging face ofbone block 278, resulting in a 5 layer bone:soft tissue:bone:softtissue:bone sandwich. This 5 membered sandwich is held together bybiocompatible connectors 272, as described herein, preferablyinterference pins, more preferably pin of cortical bone that provide aninterference fit. Preferred pins are cortical bone pins. FIG. 27B is atop view of the assembled BTB wherein the assembly appears the same asin FIG. 24B. FIG. 27C is cross-sectional side view CC of the assembledBTB, clearly showing three bone blocks sandwiching two portions of thelength of soft tissue (e.g., tendon) as those portions in turn sandwichthe central bone block. The assembly is held together at each end bybiocompatible connectors 272, preferably interference pins, morepreferably cortical bone pins providing an interference fit. FIG. 27D isa side view of the outside face of the assembled BTB clearly showing thesoft tissue sandwiched between opposing bone blocks at each end. In eachof the 5 layered (bone:soft tissue:bone:soft tissue:bone) sandwiches ateach end of the assembled BTB, there are four bone tendon interfaces andthree bone blocks. In a BTB of the present invention, at least one ofthe bone blocks must be a bone block of the present invention. It isalso within the scope of the present invention that 2 or all three ofthe bone blocks of the sandwich are an intermediate bone block of thepresent invention. However, it is also within the scope of the inventionthat 1 or 2 of the 3 bone blocks of the sandwich have a texturedsurface. For example, in one embodiment, the center bone block of thesandwich has teeth that are angled toward the direction of pull of thesoft tissue. In this embodiment, it must be kept in mind that thedirection of pull of the tendon reverses on opposing sides of thecentral bone block. In an alternate embodiment, a groove (not shown) isincluded in the design to accommodate the soft tissue that is externalto the bone block assembly.

FIGS. 28A-28D are views of another embodiment of a BTB of the presentinvention comprising two segments of soft tissue of different lengths(shown) as members of a 5 layer assembly of bone and soft tissue at eachend. In this embodiment, the two segments of soft tissue may have thesame or different widths, or areas, or they may come from differentsources or species. In another embodiment (not shown), the lengths ofsoft tissue are the same. FIG. 27A is a perspective view of a doubletendon (soft tissue) BTB 280 comprising layers of bone:softtissue:bone:soft tissue:bone. In FIG. 28A, there is a first segment ofsoft tissue 283B of a predetermined length and a second segment of softtissue 283A of a longer predetermined length. Typically the differencein length between the two segments of soft tissue in this embodimentranges from 1 mm to 10 mm depending upon surgical or anatomicalrequirements influenced by factors such as age, sex, physical size andactivity level of the intended patient as well as the nature of injuryand any complicating factors such as additional injuries or previouscondition of the patients knee. Preferably, the difference in lengthbetween the two segments of soft tissue in this embodiment ranges from 1mm to 8 mm, more preferably from 1 mm to 5 mm, most preferably 1 mm to 3mm. The length of the first segment of soft tissue 283B determines thelength of this BTB because the additional length in the second segmentof soft tissue 283A is allowed to bow as shown in FIGS. 28A, 28C and28D. At the first opposing end (the proximal end in FIG. 28A) of the BTB280, there is a five membered sandwich comprising in ascending order:bone block 284 having a tissue engaging face, a first end of soft tissuesegment 283B, bone block 285 having two tissue engaging faces, a firstend of soft tissue segment 283A, and bone block 289 having a tissueengaging face engaging the first end of soft tissue segment 283A. At thesecond opposing end (the distal end in FIG. 28A) of the BTB 280, thereis a five membered sandwich comprising in ascending order: bone block284 having a tissue engaging face, a first end of soft tissue segment283B, bone block 285 having two tissue engaging faces, a first end ofsoft tissue segment 283A, and bone block 289 having a tissue engagingface engaging the first end of soft tissue segment 283A. Each of thefive layered sandwiches is held together as a unit by biocompatibleconnectors 272 as described herein (e.g., screws, pins), preferablyinterference pins, more preferable cortical bone pins. In FIG. 28B is atop view of the assembled BTB wherein the assembly appears the same asin FIG. 24B. FIG. 28C is a side view of the assembled BTB, clearlyshowing three bone blocks sandwiching two distinct lengths of softtissue (e.g., tendon) 283A and 283B, as those lengths of soft tissuesandwich the central bone blocks 285 and 287 at their opposing ends.FIG. 28D is an end view of the BTB of FIG. 28A showing the longer softtissue segment 283A extending beyond the plane of the bone blocks andthe 5 membered sandwich. In each of the 5 layered (bone:softtissue:bone:soft tissue:bone) sandwiches at each end of the assembledBTB, there are four bone tendon interfaces and three bone blocks. In aBTB of the present embodiment, at least one of the bone blocks must be abone block of the present invention. It is also within the scope of thepresent embodiment that 2 or all three of the bone blocks of thesandwich are an intermediate bone block of the present invention.However, it is also within the scope of the present embodiment that 1 or2 of the 3 bone blocks of the sandwich have a textured surface. Forexample, in one embodiment, the center bone block of the sandwich hasteeth that are angled toward the direction of pull of the soft tissue.Although this embodiment shows the use of two biocompatible connectors272 in each bone block-tendon assembly (5 layered sandwich), it iswithin the scope of this invention to employ up to 9 biocompatibleconnectors, typically 3-5.

FIGS. 29A-29D are views of a dual tendon BTB 290 that is a hybrid ofFIGS. 28A and 24A insofar as the bone-tendon assembly at the firstopposing end is a three layer sandwich and at the second opposing end isa five layer sandwich. FIG. 29A is a is a perspective view of a doubletendon BTB 290 comprising 3 layers of bone:soft tissue:bone at one endand 5 layers of bone:soft tissue:bone:soft tissue:bone at the opposingend. In FIG. 29A, the length of soft tissue 293 has two segments 293Aand 293B coming from a single segment 293 between bone blocks 294 and295. In one embodiment, the single segment of soft tissue is merelysliced down the middle at one end to produce a “Y” shaped tissue havingsegments 293A and 293B. In another embodiment, separate and distinctsoft tissue segments 293A and 293B (typically, tendons or ligaments) arestapled, glued, sutured, woven or braided together to form singlesegment 293. In this latter embodiment, the soft tissue segments may bethe same or different, and they may be of the same or different lengths,widths, areas, sources or species. Typically, the split is stapled,glued, sutured, woven, braided or clamped together or with an additionalpiece of soft tissue in order to support or control the location of thesplit in the “Y” geometry. The FIG. 29B is a top view of the assembledBTB wherein the assembly appears substantially the same as in FIG. 24B.The number and placement of the biocompatible connectors 292 in thisembodiment (or any other embodiments herein) may vary from one boneblock assembly to another. FIG. 29C is a side view of the assembled BTB,clearly showing three bone blocks sandwiching two distinct lengths ofsoft tissue (e.g., tendon) 293A and 293B at one end and two bone blocks294 and 295 sandwiching a single length of soft tissue 293 at theopposing end. The assembly is optionally held together at each end by2-3 biocompatible connectors 292 as described herein (e.g., screws,pins), preferably interference pins, more preferable cortical bone pins.FIG. 29D is an end view of the BTB of FIG. 29A showing the longer softtissue segment 293A extending above the plane of the bone blocks.

FIGS. 30A-30B are side and end views, respectively, of a harvested BTB300 having a tendon 303 of a first defined length L1 naturally attachedat its first end to a first bone block 301 and naturally attached at itssecond end to a second bone block 302. FIGS. 30C and 30D are side andend views, respectively, of spacers 306 and 307 for increasing thelength of bone (and reducing the exposed length of tendon) in anassembled BTB of FIG. 30E. Spacers 306 and 307 are shown as being thesame length. However, it is also within the scope of the presentinvention that their lengths are different. Bone blocks 309 and 308 areoptional and are used to cap the exposed tendon sandwich. These boneblocks may have a smooth tissue engaging surface, a textured tissueengaging surface (such as shown in FIGS. 6A or 7A), or be intermediatebone blocks of the present invention. Preferably, they are anintermediate bone block of the present invention. Also, it is within thescope of the invention that the outside edges of the caps be rounded orthat in FIG. 30D, that bone block 308 be semi-circular or semi-ovularinstead of rectangular (as shown). FIGS. 30E and 30F are side and endviews, respectively, of an assembled bone block wherein the length L1 ofthe tendon in a harvested BTB has been reduced to length L2 byassembling spacers 306 and 307 to opposing naturally attached boneblocks 302 and 301, respectively. The tendons are capped at each end bybone blocks 308 and 309 and the sandwich comprising cap (bone block),tendon and naturally attached bone block, and spacer block are formedinto a unitary assembled device by insertion of biocompatible connectors305 that traverse each component of the assembly. The biocompatibleconnectors 305 (e.g., screws, pins) are any mechanical connectors thatare disclosed herein, preferably interference pins, more preferablycortical bone pins providing an interference fit. In an alternateembodiment, one or both spacers 306 or 307 may be omitted or replacedwith a bone block of approximately equal size to the naturally attachedbone block. The bone block used in place of the spacer is anintermediate bone block of the present invention or other bone block.

FIGS. 31A-31D are views of an alternate embodiment of an intermediatebone block of the present invention. FIG. 31A is a perspective view ofintermediate bone block 310 having a channel of uniform width therein.The channel is defined by a sloped floor 317 (relative to tissueengaging surface 316) and substantially parallel sidewalls 311. However,in other related embodiments that are not shown, it is also within thescope of the present invention that the sidewalls diverge or convergedepending upon perspective. FIG. 31B is a top view of the intermediatebone block looking directly down at the central channel withsubstantially parallel side walls 311 and sloped floor 317. FIG. 31C isa side view of the intermediate bone block showing the slope of thefloor 317 in the central channel. FIG. 31D is an end view of theintermediate bone block of FIG. 31A looking up the channel at slopingfloor 317. Although the present embodiment can be used with the softtissue extending from end 314 having the shallow end of the channel orend 315 having the deep end of the channel, it is preferred that thesoft tissue extend from end 314 having the shallow end of the channel.

FIGS. 32A-32D are views of an alternate embodiment of an intermediatebone block of the present invention. FIG. 32A is a perspective view ofintermediate bone block 320, having a converging channel ofsubstantially uniform depth. The converging channel is defined by floor327 of substantially uniform depth (relative to the tissue engagingsurfaces 326) and sidewalls 321 that converge as the walls extend fromend 325 to opposing end 324. FIG. 31B is a top view of the intermediatebone block 320 showing the channel with floor 327 and converging sidewalls 321. While the side walls are shown at wide divergence at end 325,it is also within the scope of the present invention that the sidewalls321 be relatively closer together than shown in FIG. 32B at end 325 andthat the angle of convergence be from 1° to 12° relative to a centerline in the channel. FIG. 31C is a side view of the intermediate boneblock showing that the channel with floor 327 is of a substantiallyuniform depth. FIG. 31D is an end view of the intermediate bone block ofFIG. 31A looking down the channel from end 325 at converging sidewalls321.

FIGS. 33A-33E are views of a template (jig) 300 used to assemble one endof a BTB (i.e., a bone block-tendon assembly). FIG. 33A is an explodedview of the template 300 showing the upper half 334 and lower half 333,and the four tensioning screws 336 for compressing upper half 334against lower half 333. Lower half 333 has 4 threaded (tapped) holes 338for receiving the 4 threaded screws 336. The lower half also has cavity331 which is sized for receiving two or more bone blocks of definedlength and width and height and segments of soft tissue of predefinedlength and width. There is a template for each bone block-tendonassembly of defined length, width and height. Cavity 331 is defined inpart by side walls 333A and 333B which also act as stops when upper half334 is compressed against lower half 333 by engagement of tensioningscrews 336. In practice, the tensioning screws compress the correctlypositioned bone and soft tissue segments placed in cavity 331 to theproper tension which is achieved at the engagement of the stops betweenthe upper and lower halves. Because the holes are predrilled by acommercially available computer driven drill press or lathe, the holes332 are merely guides for use in inserting (driving) pins into theproperly aligned components of the bone block-soft tissue assembly. FIG.33B is a perspective view of the assembled template 330 which in thislocked position would place a standard amount of tension on thepre-sized bone blocks and soft tissue placed therein prior to insertionof any pins. FIG. 33C is a top view of the assembled template. FIG. 33Dis a front view of the assembled template showing opening 339 where thesegment of soft tissue (e.g., tendon) would extend outside the device.FIG. 33E is a side view of the assembled template.

FIGS. 34A-34D provide views of another embodiment of an assembled BTB340 of the present invention wherein a single segment of soft tissue(e.g., tendon or ligament) 343 is doubled back around a bone block 345to provide a double tendon BTB. Typically, the doubled up segment of thetendon is stapled, glued, sutured, woven, braided or clamped together orwith an additional piece of soft tissue to prevent slippage of onetendon face against the other. FIG. 34A is a perspective view ofassembled BTB 340 having an intermediate bone block 344 of the presentinvention sandwiching the doubled up soft tissue 343A between opposingbone block 346. Opposing bone block 346 has a surface that is smooth,textured or that has the cavities or channels that characterize theintermediate bone block of this invention. The bone block-soft tissue(e.g., tendon) assembly at the proximal end of FIG. 34A comprising boneblock 344, soft tissue 343A and bone block 346 is held together as aunit by biocompatible connectors 342, as described herein (e.g., screws,pins), preferably interference pins, more preferable cortical bone pins.FIG. 34B is a top view of the BTB where the biocompatible connectors(e.g., interference pins) in the top of the opposing bone block areclearly visible. FIG. 34C is a side view showing tendon 343 doublingback on itself around bone block 345 at the left side of the figure, andshowing bone block 344, soft tissue 343A and bone block 346 heldtogether as a unit by biocompatible connectors 342 at the right side ofthe figure. FIG. 34D is an view of the bone block-soft tissue assemblyat the proximal end of the BTB 340, as it is positioned in FIG. 34A,showing the bone blocks 344 and 346 sandwiching the doubled up tendon343A, all being held together as a unitary assembled structure bybiocompatible connector 342. In an alternate embodiment, a groove (notshown) is included in the design to accommodate the soft tissue that isexternal to the bone block assembly.

FIGS. 35A-35D provide views of another embodiment of an assembled BTB ofthe present invention wherein a single segment of soft tissue (e.g.,tendon or ligament) is doubled back to provided a double tendon BTB.This embodiment is a variation of the embodiment of FIG. 34 but furtherincludes at the turnabout end two additional bone blocks 357 and 359that sandwich the reversing ends of tendon 353 to central bone block355, and allow both ends of the resulting BTB 350 to provide for maximumbone to bone contact between the graft and the patient's bone when thegraft is implanted in a surgically excised bone tunnel in a patient.FIG. 35A is a perspective view of the assembled BTB 350 as describedabove. FIG. 35A shows BTB 350 having at the proximal end in the figurean intermediate bone block 354 of the present invention having its softtissue engaging face engaging one face of the doubled up soft tissue353A, while bone block 356 has its soft tissue engaging face engagingthe opposing face of the soft tissue. The resulting assembly of thethree respective layers are sandwiched one on top of the other and areheld together as a unit by biocompatible connectors 352, as describedherein (e.g., screws, pins), preferably interference pins, morepreferable cortical bone pins. Although 2 biocompatible connectors areshown, it is within the scope of the present embodiment that from 2-5biocompatible connectors be used. At the distal end of the BTB 350 shownin FIG. 35A, there is a five layer sandwich comprising in stacked formfrom bottom to top: bone block 357, soft tissue 353, central bone block355, soft tissue 353, and bone block 359. This 5 layer stacked assemblyis held together as a unit by biocompatible connectors 352, as describedherein (e.g., screws, pins), preferably interference pins, morepreferable cortical bone pins. In this 5 layer assembly, at least one ofbottom bone block 357, central bone block 355 or capping bone block 359is an intermediate bone block of the present invention having its softtissue engaging face engaging one face of tendon 353; preferably two areintermediate bone blocks, more preferably, all three are intermediatebone blocks of the present invention. FIG. 35B is a top view of the BTB350 where the biocompatible connectors 352 in the tops of the opposingbone block-soft tissue assemblies are clearly visible. FIG. 35C is aside view showing tendon 353 doubling back and forming theabove-described five layer sandwich at the left end of the figure andthe above described three layer sandwich at the right end of the figure.FIG. 35D is a view of the proximal end of the BTB 350, as positioned inFIG. 35A, showing the three layer bone-soft tissue assembly (sandwich)as one looks down the length of the BTB 350. In an alternate embodiment,a groove (not shown) is included in the design to accommodate the softtissue that is external to the bone block assembly.

FIGS. 36A-36D are a series of views of another embodiment of anassembled BTB of the present invention. FIG. 36A is a perspective viewof assembled BTB 360 comprising a length of soft tissue 363 havingopposing first and second ends, wherein the first end of the soft tissueis sandwiched between wedge shaped opposing bone blocks 366 and 364, theangle of the wedges being such that in combination, the wedges form a 3dimensional shape whose opposing longitudinal surfaces are substantiallyparallel. This results in an intermediate bone block where the boneblock (364, 366) has a lengthwise tapering (wedge shaped) profile. Theresulting wedge (366): soft tissue (363): wedge (364) sandwich is heldtogether as a unit by suitable biocompatible connectors 362, asdescribed herein (e.g., screws, pins), preferably interference pins,more preferable cortical bone pins. Likewise, the second end of thelength of soft tissue 363 is sandwiched between wedge shaped opposingbone blocks, the angle of the wedges being such that in combination, thewedges form a 3 dimensional shape whose opposing longitudinal surfacesare substantially parallel. This resulting wedge (365):soft tissue(363): wedge (364} sandwich is also held together as a unit by suitablebiocompatible connectors 362, as described herein (e.g., screws, pins),preferably interference pins, more preferable cortical bone pins.Moreover, at least one of the opposing wedge shaped bone blocks 364 ateach end of the length of soft tissue 363 has cavities or channels 367such that it is an intermediate bone block of the present invention.FIG. 36B is a top view of this embodiment of assembled BTB 360. FIG. 36Cis a side view of assembled BTB 360 showing the assembly details and theuse of suitable biocompatible connectors. FIG. 34D is a view of theproximal end of assembled BTB 360 as positioned in FIG. 36D.

EXAMPLE 1 Intermediate Bone Blocks of the Invention Having anOmega-Shaped Cross-Section

A. Plank with Two Substantially Parallel Channels Having an Omega-ShapedCross-Section:

Cortical bone from a long bone shaft was cut into planks using a bandsaw. Bone planks were then cut into rectangular bone blanks of roughdimensions 10 mm×5 mm×25 mm using a mill (Haas Automation, Oxnard,Calif.; model # TM-1, serial # 34798). Each blank is then squared up andsurface cut (planed) to final dimensions. One of the squared up boneblanks was laid out and templated for cutting two channels running thelength of the bone blank and substantially parallel to the sidewalls ofthe bone blank. The rough outlines of the omega-shaped channels were cutwith a 1.0 mm diameter end mill cutter. A 2.4 mm diameter ball end mill(Dremel, Racine Wis.; Dremel # 107) was used to complete theomega-shaped channels as shown in FIG. 11, for the final dimensions of1.8 mm deep.

B. Plank with a Single “U”-Shaped Layout of Channel having anOmega-shaped Cross-section:

Cortical bone from a long bone shaft was cut into planks approximatelyxx mm thick using a band saw. Bone planks were then cut into rectangularbone blanks of rough dimensions 10 mm×5 mm×25 mm using a mill (HaasAutomation, Oxnard, Calif.; model # TM-1, serial # 34798). One of thebone blanks was laid out and templated for cutting a triple “U” shapedchannel running the length of the bone blank and having its linearportions substantially parallel to the sidewalls of the bone blank. Therough outline of the omega-shaped channel was cut with a 1.0 mm diameterend mill cutter. A 2.4 mm diameter ball end mill (Dremel, Racine Wis.;Dremel # 107) was used to complete the omega-shaped channel as shown inFIG. 17, for the final dimensions of 1.8 mm deep.

C. Plank with a Triple “U”-Shaped Layout of Channel Having anOmega-shaped Cross-section:

Cortical bone from a long bone shaft was cut into planks approximatelyxx mm thick using a band saw. Bone planks were then cut into rectangularbone blanks of rough dimensions 10 mm×5 mm×25 mm using a mill (HaasAutomation, Oxnard, Calif.; model # TM-1, serial # 34798). One of thebone blanks was laid out and templated for cutting a triple “U” shapedchannel running the length of the bone blank and having its linearportions substantially parallel to the sidewalls of the bone blank. Therough outline of the omega-shaped channel was cut with a 1.0 mm diameterend mill cutter. A 2.4 mm diameter ball end mill (Dremel, Racine Wis.;Dremel # 107) was used to complete the omega-shaped channel as shown inFIG. 17, for the final dimensions of 1.8 mm deep.

D. Semi-Capsule Shaped Intermediate Bone Block;

An intermediate bone block from Example 1 with its omega-shaped channelsfacing downward is clamped in place in a corner round cutter. The cutterblade is set to impart a 5 mm hemispherical radius on the end of the 10mm wide 5 mm high bone block. Once the first end is cut, the bone blockis reversed in the cutter, clamped in place, and the second end is cutto produce a bone block having a semi-hemispherical end. The bone blockis then placed in a router having a 5 mm circular blade and each sidewall is cut to impart a 5 mm radius. The result is a semi-capsularshaped intermediate bone block of FIG. 20.

In a more efficient method, two block ends can be cut simultaneously.Two intermediate bone blocks from Example 1 (or two blank bone planks)are manually joined together with their tissue engaging faces engaging(contacting) one another. The pair of blocks are then clamped in placein a lathe with a blade having a 5 mm radius. The blocks are slowly fedinto the lathe until the radius has been cut resulting in ahemispherical end. The pair of blocks are released and then reversed inthe lathe so that the opposing end can be cut. Once the opposing end iscut, the bone block is then placed in a router having a 5 mm circularblade and each side wall is cut to impart a 5 mm radius. The result is asemi-capsular shaped intermediate bone block of FIG. 20.

EXAMPLE 2 Bone Block Assembly Comprising an Intermediate Bone Block anda Second Bone Block

A. Bone Block of FIGS. 6A-6D with Saw Tooth Pattern of Ridges

Cortical bone planks were cut from a long bone shaft using a band saw.Bone planks were then cut into rectangular bone blanks of roughdimensions 10 mm×5 mm×25 mm using a mill (Haas Automation, Oxnard,Calif.; model # TM-1, serial # 34798). The mill was used to cut theserrated pattern of FIGS. 6A-6D on the upper block from a bone blank, at0.76 mm deep, with a pitch of 0.8 teeth per mm, and at tooth angle of 30degrees.

B. Intermediate Bone Block of FIGS. 11A-11D

The bone block of Example 2A was clamped to a surface with its ridgeside up and the rough outline of two substantially parallel channelswith an omega-shaped cross section were cut into the block with a 1.0 mmend mill cutter. A 2.4 mm diameter ball end mill (Dremel, Racine Wis.;Dremel # 107) was used to complete the two omega-shaped channels toproduce the intermediate bone block of FIG. 11.

EXAMPLE 3 A Bone Tendon Assembly for Testing Grip of Bone Patterns

A. Bone Block with a Smooth Tendon Engaging Surface

Cortical bone from a long bone shaft were cut into planks using a bandsaw. Bone planks were then cut into rectangular bone blanks of roughdimensions 10 mm×5 mm×25 mm using a mill (Haas Automation, Oxnard,Calif.; model # TM-1, serial # 34798). Each blank is then squared up andsurface cut (planed) to final dimensions. A pair of these bone blockswere used to make the bone block-tendon assembly of FIG. 1.

B. Bone Block with a Saw Tooth Pattern on the Tendon Engaging Surface of0.8 Teeth per mm, 0.76 mm deep, at a 30 Degree Angle to the Direction ofPull of the Tendon

Cortical bone planks were cut from a long bone shaft using a band saw.Bone planks were then cut into rectangular bone blanks of roughdimensions 10 mm×5 mm×25 mm using a mill (Haas Automation, Oxnard,Calif.; model # TM-1, serial # 34798). The mill was used to cut theserrated pattern of FIGS. 6A-6D on the block at 0.76 mm deep, with apitch of 0.8 teeth per mm, and at tooth angle of 30 degrees. This boneblock was used to make the bone block-tendon assembly in each of FIGS.2A-B, 3A-B, 4A-D, 5A-D. It was also used as the opposing bone block toeach of the bone blocks of designs 01-05 as reported in Table 2.

C. Intermediate Bone Block of the Invention with 2 Channels Having aRectangular Cross-Section

Cortical bone planks were cut from a long bone shaft using a band saw.Bone planks were then cut into rectangular bone blanks of roughdimensions 10 mm×5 mm×25 mm using a mill (Haas Automation, Oxnard,Calif.; model # TM-1, serial # 34798). The mill was used to cut theserrated pattern of FIG. 6 on the upper block from a bone blank, at 0.76mm deep, with a pitch of 0.8 teeth per mm, and at tooth angle of 30degrees. The other bone block was machined with channels of arectangular cross section. This intermediate bone block (dimensions of25 mm×11 mm×4 mm) was machined using an end mill bit dimensioned 1.6 mmwide×2 mm deep at a placement of 2.5 mm off center. Tendon was placedbetween the two blocks, the blocks where then clamped to 250 Newtons,and the free end of the tendon was mechanically clamped and pulled untilfailure occurred.

D. Standardized Tendon for use in Testing Load Strength of a BoneBlock-Tendon Assembly

Tendons selected for testing were generally about 150 mm in length,about 8 mm in width, and about 2-3 mm in thickness. Tibialis tendonswere preferred.

EXAMPLE 5 Method of Testing Bone Block—Tendon Assemblies for LoadStrength

Bone block assemblies having different combinations of tendon engagingfaces were used to sandwich a standardized length, width and thicknessof tendon from Example 4D. The individual bone blocks of the bone blockassemblies had a documented size of 25 mm×10 mm of tendon engaging face.The tendon engaging face differed from one another solely in the surfacefeatures that were being comparatively tested. Five combinations of boneblock assemblies that were tested and reported in Table 1 comprised thefollowing combinations of tendon engaging surfaces: smooth:smooth;smooth:ridges (saw tooth pattern); ridges (saw tooth pattern):ridges(saw tooth pattern); ridges (saw tooth pattern):2 square channels indirection of pull; and ridges (saw tooth pattern):2 omega channels indirection of pull.

The five combinations of bone block assemblies that were tested in Table2 comprised the following combinations of tendon engaging surfaces:design 01 (double “I” layout of omega channels:ridges (saw toothpattern)); design 02 (inverted “U” layout of omega shaped channel:ridges (saw tooth pattern)); design 03 (deep inverted “U” layout ofomega shaped channel: ridges (saw tooth pattern)); design 04 ((“A”shaped layout of omega shaped channel: ridges (saw tooth pattern)); anddesign 05 (double “A” layout of omega shaped channels: ridges (saw toothpattern)).

Each of these five combinations were tested for their ability to hold atendon until failure in response to an increasing tendon load measuredin Newtons. Testing was accomplished by sandwiching an equal length oftendon from Example 4D between the tendon engaging faces of the opposingbone blocks. The sandwich was then placed in one end of an Instron Model5800 (Canton Mass.) and compressed to 250 Newtons in a pneumatic grip.The opposing end of the tendon was securely clamped in the Instronbetween two pieces of textured metal to avoid slippage. The Instron loadcell measured the load (force in Newtons) that resulted in failure ofthe bone block-tendon assembly, i.e., the load required to pull thetendon from the clamped bone blocks. This test was run in triplicate oneach bone block-tendon combination and average of the three loads wasdocumented and is reported in Tables 1 and 2 herein.

EXAMPLE 6 BTB having a Naturally Attached Bone at One End and a BoneBlock Assembly of the Present Invention at its Opposing End

The tendon and bone used to make this example were recovered usingprocedures common to those skilled in the art. The soft tissue graftshaving a material specifications were prepared to those dimensions. Forexample, the Achilles specifications were, 10 mm bone block diameter,and the non-bone end trimmed to an overall length of 200 mm.

Cortical bone planks were cut from a long bone shaft using a band saw.Bone planks were then cut into rectangular bone blanks of roughdimensions 10 mm×5 mm×25 mm using a mill (Haas Automation, Oxnard,Calif.; model # TM-1, serial # 34798). The mill was used to cut theserrated pattern of FIG. 6A on the upper block from a bone blank, at0.76 mm deep, with a pitch of 0.8 teeth per mm, and at tooth angle of 30degrees. The other bone block was machined with channels of an omegacross section. The rough outline of the omega channels were cut into thelower block with a 1.0 mm end mill cutter. A ball end mill (Dremel,Racine Wis.; Dremel # 107) was used to complete the omega channel ofFIG. 11 in the lower block. Cortical pins (Ø 2 mm×15 mm) were machinedfrom the bone plank of rough dimensions 5 mm×5 mm×20 mm using a lathe(Omnitum, Farmingdale, N.Y., Model # TO-CNC, serial # 3282G5AHB). Bonehaving density from about 1.82 g/cm3 to 1.96 g/cm3 was preferred forboth the bone blocks and the cortical pins. An assembly fixture, asshown in FIGS. 33A-33F was used to hold the upper and lower bone blocksin place for the remainder of the assembly procedure. The free end ofthe Achilles tendon was placed between the two blocks, the blocks wherethen clamped in the assembly fixture. Holes for the cortical pins werethen drilled through the bone block assembly using the guide holes (seeFIG. 33) in the assembly fixture. The cortical pin holes were cleanedusing a reamer. The cortical pins were press fit into place, then groundor cut even with the surface of the bone block after removal from theassembly fixture.

While the invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the invention without departing from its scope.Therefore, it is intended that the invention not be limited to theparticular embodiment disclosed, but that the invention will include allembodiments falling within the scope of the appended claims.

1. A bone block assembly for securing soft tissue, said bone blockassembly comprising two to ten components of cortical bone, cancellousbone, artificial bone or a combination thereof, wherein said soft tissueis sandwiched between at least two of said components, and saidcomponents being connected by one to ten biocompatible connectors, atleast two of said components having opposing tissue engaging surfacesthat contact opposing sides of said soft tissue, at least one of saidtissue engaging surfaces comprising a textured face, and at least oneother of said tissue engaging surfaces comprising: a face comprisingcompression surfaces and one to ten channels, said compression surfacesfor compressing said soft tissue against the opposing face, and said oneto ten channels for receiving overflow soft tissue from said compressionsurfaces; wherein said one to ten channels have an undercutcross-sectional profile and are laid out across said tissue engagingsurface in a nested configuration along the direction of pull of saidsoft tissue.
 2. The bone block assembly of claim 1, wherein saidcomponents comprise cortical bone, cancellous bone or both.
 3. The boneblock assembly of claim 1, further comprising one to ten machined holesthat traverse either the bone block assembly as a whole or a singlecomponent thereof.
 4. The bone block assembly of claim 1, furthercomprising a depression on at least one of said components that aids insurgical placement.
 5. The bone block assembly of claim 1, wherein saidcomponents have an outer surface that is shaped to aid in surgicalplacement.
 6. The bone block assembly of claim 5, wherein the outersurface has a shape selected from the group consisting of polygonal,cylindrical, threaded, bulleted, chamfered, angled, ridged, capsuleshaped, tapered and a combination thereof.
 7. The bone block assembly ofclaim 5, wherein the outer surface contains spikes or indentations. 8.The bone block assembly of claim 1, wherein at least one of saidcomponents comprise one to five grooves on an outer surface toaccommodate one or more interference screws.
 9. The bone block assemblyof claim 8, wherein said grooves comprise threads or tapped threads. 10.The bone block assembly of claim 8, further comprising two equallyplaced grooves on an outer surface to accommodate one or moreinterference screws.
 11. The bone block assembly of claim 1, furthercomprising a groove on an outer surface of said bone block assembly toaccommodate said soft tissue.
 12. The bone block assembly of claim 1,wherein any of said components comprise an internal leading edgeconfiguration that reduces tissue stresses during assembly and use. 13.The bone block assembly of claim 1, wherein at least one of the opposingfaces contain a lengthwise tapering profile.
 14. The bone block assemblyof claim 1, wherein said undercut cross-sectional profile is an omegacross-sectional profile.
 15. The bone block assembly of claim 1, whereinsaid channels comprise a cross-sectional profile selected from the groupconsisting of triangular, dovetail, omega and a combination thereof. 16.The bone block assembly of claim 1, wherein all of said tissue engagingsurfaces are textured.
 17. The bone block assembly of claim 16, whereinsaid textured face comprises rows of ridges running across the intendeddirection of pull of the soft tissue.
 18. The bone block assembly ofclaim 17, wherein at least one of said channels comprises an omega crosssectional profile.
 19. The bone block assembly of claim 1, wherein atleast one of said components is perfused or coated with anosteoinductive substance.
 20. The bone block assembly of claim 1,wherein at least one of said components has an outer surface that ispartially demineralized.
 21. The bone block assembly of claim 1, whereinat least one of said components is cleaned or perfused by treatment withan alternating pressure cycling process.
 22. The bone block assembly ofclaim 1, wherein at least one of said components are themselvesassembled from smaller portions of cortical bone, cancellous bone,artificial bone or a combination thereof.
 23. A bone block assembly forsecuring soft tissue, said bone block assembly comprising two componentsof cortical bone, cancellous bone, artificial bone or a combinationthereof, wherein said soft tissue is sandwiched between said twocomponents, and said components being connected by one to tenbiocompatible connectors, said two components having opposing faces forcontacting opposing sides of said soft tissue, wherein one of said twocomponents has a textured face, and the other of said two components hasa face comprising one or more compression surfaces and one to tenchannels, said compression surfaces for compressing said soft tissueagainst the opposing face, and said channels for receiving overflow softtissue from said compression surfaces; wherein said channels comprise anundercut cross-sectional profile and are laid out across the face in anested configuration along the direction of pull of said soft tissue.24. The bone block assembly of claim 23, wherein said undercutcross-sectional profile comprises an omega profile.
 25. The bone blockassembly of claim 23, wherein the textured face comprises rows of ridgesrunning across the intended direction of pull of the soft tissue.